In case of imperative sentence, where we give some order, we use 'let'. And 'let' always takes 'be'.

In case of imperative sentence (case of advise), word 'advised' is used. Hence, option 3.

While changing the voice, we interchange the respective places of the subject and the object. In passive voice, we always use the third form of the verb with the helping verb. 'Expect' (present simple) changes into 'is expected' (as the subject 'the news' is singular).

Noun clause (this carpet) does not change the voice. Verb clause (needs dusting) should be changed to 'needs to be dusted', as we use the third form of the verb for the work that needs 'to be' accomplished.

This is the case of an advise (imperative sentence). Hence, option 3.

While changing the voice, we interchange the respective places of the subject and the object. In passive voice, we always use the third form (in this case 'is done') of the verb with the helping verb. First person 'I/We' takes 'shall'.

The noun clause (milk) remains unchanged; only the verb clause (tastes sweet) needs to be changed. Case of present simple tense. Hence, option 2 is the correct choice.

The noun clause (quinine) remains unchanged; only the verb clause (tastes bitter) needs to be changed. Case of present simple tense. Hence, option 2 is the correct choice.

The noun clause (it is the time) will not change the voice. Verb clause (to ring the bell) needs to be changed into passive voice. 'For the bell to be rung' is the correct replacement, as we use the third form of the verb in the passive voice.

While changing the voice, we interchange the respective places of the subject and the object. In passive voice, we always use the third form of the verb with the helping verb.

This is the case of 'request' (imperative sentence) as shown by the word 'kindly'. Hence, option 4.

This is the case of an advise; and to give advise, we use modal 'should'.

A noun clause never changes its voice. The verb clause (to write with) needs to be changed. 'To be written with' is the correct replacement. Hence, option 3.

The noun clause (my warning) does not change its voice. The verb clause (they take no notice) needs to be changed. Option 3 is the correct usage as we use the third form of the verb along with the verb in the passive voice.

In passive voice, subject (who) becomes the object (by whom). In interrogative sentences, verb precedes the subject. And in continuous tenses, 'being' shows the continuity (in passive voice).

The given sentence is in present simple tense, and none other 'auxiliary' confirms to the same tense, except 'are'. 'Are being' is used in case of present continuous tense. Hence, option 1.

The given sentence is in present simple tense, and none other auxiliary, except 'is', confirms to the same tense. 'Known to' is the correct usage. Hence, option 4.

Whenever the subject is missing in the passive voice, we provide the same while changing into the active voice. Indefinite pronoun 'someone' is the correct subject supplied. Hence, option 4.

Option (1) changes the tense, option (2) does not convert into passive voice and option (3) does not retain the interrogative (used 'a pen is' in place of 'is a pen').

When we propose or affirm something, we use 'it is proposed to do..........'. Hence, option 4.

This is the case of an advise; and to give advise, we use modal 'should'.

This is the case of an advise; and to give advise, we use modal 'should'.

'Please' means that this is the case of a request. This request is made to the second person (you). Hence, option 3.

Milk is contained 'in' a pot.

Verb clause (prosper) becomes (be blessed by prosperity) in the passive voice.