Sentences expressing a request, order, advice, suggestion or prohibition are called imperative sentences. Such sentences can be changed into the passive voice in the following manner.

When we change an imperative sentence into the passive, we use a verb like request, order, suggest, advice etc. The choice of verb depends upon the exact nature of the order or request.

Active: Please lend me your pen.

Passive: You are requested to lend me your pen.

Active: Please do this work.

Passive: You are ordered to do this work.

Active: Please bring me a glass of water.

Passive: You are requested to bring me a glass of water.

Active: Work hard to pass your examination.

Passive: You are advised to work hard to pass your examination.

Active: Do it.

Passive: Let it be done.

Active: Let me do it.

Passive: Let it be done by me. OR Let me be allowed to do it.

Active: Consult a doctor.

Passive: It is suggested that you should consult a doctor.

Active: Do not pluck the flowers.

Passive: Let the flowers not be plucked. OR You are forbidden to pluck the flowers.

As you can see, we use an infinitive or a that-clause to change an imperative sentence into the passive voice.

Not all verbs can be followed by an infinitive. Some verbs are followed by that-clauses. Suggest is one of them. It is followed by a that-clause, not an infinitive.