Cleft Sentences with "what"
1)Resorts shouldn't take too many people.
(should/impose/restrictions)

Correct answer: What they should do is impose restrictions.
(Cleft sentence without "to")

2)I'm sorry but the plane is going to be delayed.
(can/offer/meal vouchers)

Correct answer: What we can do is to offer you meal vouchers.

Another example with "to" in a cleft sentence:
What I'd really like is to lie by the pool.

My question:
I couldn't found a rule when I have to use " to + verb" in a cleft sentence. However cleft sentences are mostly indicated without a "to", like in the first example (Nr. 1)

Can anyone answer my question? Thank you.

Question

Cleft Sentences with "what"
1)Resorts shouldn't take too many people.
(should/impose/restrictions)

Correct answer: What they should do is impose restrictions.
(Cleft sentence without "to")

2)I'm sorry but the plane is going to be delayed.
(can/offer/meal vouchers)

Correct answer: What we can do is to offer you meal vouchers.

Another example with "to" in a cleft sentence:
What I'd really like is to lie by the pool.

My question:
I couldn't found a rule when I have to use " to + verb" in a cleft sentence. However cleft sentences are mostly indicated without a "to", like in the first example (Nr. 1)

Can anyone answer my question? Thank you.

Answer

First, I think the second sentence is wrong. It should be, "What we can do is offer you meal vouchers."

Whether to use "to + verb" or not depends on whether a verb or noun needs to come after "is."

If a verb [i.e. action] needs to come after "is," don't use "to."
EXAMPLE: What they should do is _________ [they need to do an action/verb]
                   What they should do is impose restrictions. [impose = verb]

If a noun [i.e. thing] needs to come after "is," use "to + verb."
EXAMPLE: What I'd really like is _________ [noun]
                   What I'd really like is a book. [book = noun]
                   What I'd really like is a nap. [nap = noun]
                   What I'd really like is to lie by the pool. [to lie = noun]

REASON: "to + verb" is called an "infinitive." Infinitives are verbs that act like nouns.

Verpassen Sie nicht die Gelegenheit, bequem von zu Hause aus eine Sprache zu lernen. Stöbern Sie in unserer Auswahl an erfahrenen Sprachlehrern und melden Sie sich jetzt zu Ihrer ersten Unterrichtsstunde an!