1) Some verbs can be followed by a clause beginning with a wh-word (how, what, when, where, which, who, or why). Other verbs like this include arrange, calculate, check, choose, debate, determine, discover, discuss, establish, find out, forget, guess, imagine, know, learn, notice, plan, realize, remember, say, see, talk about, think (about), understand, wonder…
Example:
- That might explain why he’s looking unhappy.
- Let’s consider how we can solve the problem.
- I couldn’t decide which train I ought to catch.
NOTE:
ç These verbs can also be followed by a wh-word (except ‘why’) + to-infinitive.
Example:
- I don’t understand what to do.
- She calculated how much to pay on the back of an envelope.
ç But notice that if we change the subject in the wh-clause we can’t use a to-infinitive.
Example: I can’t imagine what you like about jazz. (but not I can’t imagine what to…)
2) Some verbs must have an object before the wh-clause. Other verbs like this include advise, inform, instruct, teach, warn, remind, tell…
Example:
- She reminded me where I had to leave the papers
- We told Derek and Linda how to get to our new house.
NOTE:
ç The verbs ask and show often have an object before a wh-clause, but not always.
Example: I asked (him) how I could get to the station, and he told me.
ç These verbs can also be followed by an object + wh-word + to-infinitive.
Example:
- She taught me how to play chess.
- I showed him what to look for when he was buying a second-hand car.
ç We can often use the way instead of how.
Example: Have you noticed the way he spins the ball. (or …how he spins the ball.)
3) Whether
ç We can use whether as the wh-word in a wh-clause when we want to indicate that something is possible, but that other things are also possible. Whether has a similar meaning to ‘if’.
Example:
- He couldn’t remember whether he had turned the computer off.
- Can you find out whether she’s coming to the party or not.
ç Whether can be followed by a to-infinitive, but ‘if’ is never used before a to-infinitive. Verbs that are often followed by whether + to-infinitive include choose, consider, debate, decide, determine, discuss, know, wonder…
Example: The have 14 days to decide whether to keep it or send it back.
NOTE: The difference between the pairs of sentences below. The first has a wh-clause with whether and the second has a that-clause.
Example:
- I didn’t know whether the university was shut. (= if the university was shut or not)
- I didn’t know that the university was shut. (suggests that the university was shut)
- We couldn’t see whether he was injured. (= if he was injured or not)
- We couldn’t se that he was injured. (suggests that he was injured)
