They cancelled all flights because of fog.

A. Unless the homework is easy, I will ask you for help.

B. Unless the homework is difficult, I will ask you for help.

C. Unless the homework is easy, I won’t ask you for help.

D. Unless the homework isn’t difficult, I won’t ask you for help.

A. Complaints should be sent to the head office.

A. Bicycles must not be left in the hall.

B. Bicycles in the hall must not being left.

C. Bicycles in the hall must not left.

D. Bicycles must been not left in the hall.

A. He advised me against going.

B. He told me to stay with him.

C. He asked me not to go.

D. He advised me never to go.

A. It is three months since she started work.

B. She had been working for three months.

C. She is working here for three months now.

D. It’s three months that she worked for.

A. I have started teaching for 14 years now.

B. For 14 years have I been a teacher.

C. I was a teacher for 14 years.

D. I have been a teacher for 14 years now.

A. I haven’t meet my aunt for long ago.

B. The last time I met my aunt was since years ago.

C. I last saw my aunt years ago.

D. I didn’t see my aunt years ago.