When and If
100% Original Practice Test
Help prepare a community planetarium opening. Use present forms for future time and conditions, distinguish expected events from possibilities, and practise 44 original questions plus four speaking activities.
Your Quick Grammar Guide
Choose the clause by its job: does when name the time an event is expected, does if introduce a possible condition, or is the sentence asking indirectly about an unknown future time?
How to Form It
Expected future time: when + present form
Positive: when + subject + present simple; main clause + will/can/may.
When the doors open, we’ll welcome the first visitors.
Negative: when + subject + do/does not + base verb; main clause + future/modal.
We’ll begin the talk when the projector doesn’t make a clicking sound.
Question: will + subject + base verb + when + present clause?
Will you call me when the first group leaves?
Use present simple in the when-time clause for an event expected later. The same future-time pattern is common after before, after, until and as soon as. Put the future meaning in the main clause.
Real possibility: if + present form
Positive: if + subject + present simple; main clause + will/can/may/imperative.
If the sky stays clear, we’ll use the roof telescope.
Negative: if + subject + do/does not + base verb; main clause + suitable result.
If the team doesn’t finish the check, the manager will wait.
Question: question word + will/can + subject + base verb + if + present clause?
What will you do if the roof is wet?
A real condition can be possible or uncertain. Use present simple in the if-clause, not will for the ordinary future meaning.
Completion before the later event: present perfect
Use when/if + present perfect when the action needs to be complete by the time of the result: When the guide has checked the tickets, the group can enter. If you have finished the map, you can choose a sticker.
Positive: when/if + subject + have/has + past participle. Negative: when/if + subject + haven’t/hasn’t + past participle. Question: Will you be ready when the team has finished?
Remember: the main clause may use will, can, may, an instruction, or another form that fits the meaning.
Clue Words & Patterns
Expected event or real condition?
When the last visitor leaves, we’ll lock the dome. The team expects the visitor to leave; when names the time of the later action.
If the last visitor leaves early, we’ll start the film sooner. The early departure is only a possibility, so if introduces the condition.
Event or completed step?
When the guide arrives, we can start. Arrival is the future event that sets the time.
When the guide has checked the tickets, we can start. The check must be complete before starting; present perfect highlights the finished step.
When can take different jobs
Call me when the show ends. This is a time clause, so use present simple.
I don’t know when the show will end. This is an indirect question about an unknown time, so use statement word order with will.
Meaning and sentence structure decide the form. The word when alone does not ban will from every clause that follows it. The same distinction applies to if: I do not know if the show will finish on time means I do not know whether it will finish on time. This embedded question is different from If the show finishes early, we can visit the shop.
Present simple or present perfect?
Both can be natural when the sequence is clear: When you finish the map and When you have finished the map. The perfect stresses completion before the next step. A deadline such as by five does not automatically rule out the simple form. In exercises that request one form explicitly, follow the hint.
Watch Out & Common Mistakes
Future form inside a time clause
Wrong: We’ll begin when the lights will dim.
Better: We’ll begin when the lights dim.
Why: The main clause carries the future meaning; the expected event uses present simple in the when-clause.
Future form inside an ordinary condition
Wrong: If the roof will be wet, use the indoor telescope.
Better: If the roof is wet, use the indoor telescope.
Why: This is a real possible condition followed by an instruction. Use present simple in the if-clause.
Completion by a deadline
Wrong: If the team will finish the check by six, we can open.
Better: If the team has finished the check by six, we can open.
Why: Use a present form in this ordinary condition. Both finishes and has finished can fit; the perfect makes completion especially clear.
Indirect question word order
Wrong: I wonder when will the next show begin.
Better: I wonder when the next show will begin.
Why: An indirect question uses statement word order. Here when asks about an unknown future time; it is not a time clause.
Using when for an uncertain condition
Wrong for an uncertain forecast: When the clouds clear tonight, we’ll use the roof telescope.
Better: If the clouds clear tonight, we’ll use the roof telescope.
Why: The team does not know whether the clouds will clear. If shows that the event is only possible.
Missing the perfect participle
Wrong: When the visitors have take their seats, the talk can begin.
Better: When the visitors have taken their seats, the talk can begin.
Why: Present perfect uses have/has plus a past participle: take → taken.
Self-check 1: Choose the form: We’ll open the doors when the manager ___ (arrive). Why?
arrives. This is an expected future event in a when-time clause, so use present simple there.
Self-check 2: Choose the form: If you ___ (finish) the safety card by five, you can join the tour.
finish or have finished. Both can express the requirement. Present perfect emphasises completion before the tour.
Self-check 3: Which is correct: I don’t know when the show will end / when will the show end?
I don’t know when the show will end. It is an indirect question, so use statement word order. Will is possible because this clause asks about an unknown future time.
Before you answer: Decide whether when gives an expected time, if gives a possible condition, or when introduces an indirect question. Use present simple for a future event or real condition; use present perfect when completion by that point matters. Then check the main clause and word order.
Speaking: make it personal
Listen to each model, repeat it, then change the details to tell your own story. Speaking practice is for self-assessment and adds no points to the 44-question test.
Practice 1
Explain what the team will do when the first visitors arrive, and describe a step that must be complete before the show starts.
Read the model
When the first visitors arrive, we'll welcome them beside the Moon model. If the technicians have checked the projector, the guide can start the show.
Practice 2
Describe a possible change to an outdoor plan and say what the group will do if it happens.
Read the model
If the sky is cloudy tonight, we will move the telescope activity into the planetarium. If the clouds clear later, we can go outside for a short look at the Moon.
Practice 3
Give an instruction for a visitor who needs help, and include a future time clause.
Read the model
If you need help with the star map, ask Jo at the information desk. She'll explain the northern constellations when she finishes helping the next visitor.
Practice 4
Report something you do not know about an upcoming show. Use an indirect question with when.
Read the model
I don't know when the late show will finish, so I'll ask the guide before I buy a ticket.
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Learning review: what can you do now?
Can you choose when for an expected event and if for an uncertain condition? Check the present simple or present perfect in the time clause, then choose an appropriate main clause. Explain how an indirect question differs.