1 The children have been told about the party.

2 Students are expected not to talk during the examination.

3 This button mustn't be touched while the experiment is in progress.

4 The flowers should be kept in a warm sunny place.

5 This machine must be cleaned every time it is used.

6 The bill had to be paid before the hotel was left.

1.the children have been told about the party.

2.Students are expected not to talk during the examination.

3. This button mustn't be touched while the experiment is in progress.

4.the flowers should be kept in a warm sunny place.

5. This machine must be cleaned every time it is used.

6. The bill had to be paid before the hotel was left.