They took measures to prevent poisonous gases from escaping．

A pl<u>ay</u>s B d<u>ay</u>s C s<u>ay</u>s D p<u>ay</u>s

A we are going home B we go home C we went home D we can go home<br/>

A read B being read C reading D having read<br/>

A have B has C have been D has been<br/>

A to send B to be sending C to have sent D to have been sending<br/>

A count on B count in C count up D count out<br/>

A to stay B is to stay at C to stay at D is for staying<br/>

A is as good or better than the new hotel B are as good or better than the new hotel C is as good as or better than that of the new hotel D are as good as or better than those of the new hotel<br/>

A intention B attempt C purpose D desire<br/>

A can't have been B shouldn't have been C mustn't have been D wouldn't have been<br/>