My uncle is a_________in the study of birds and their actions to pollution.

A. They know why teenagers value friendship.

B. They read  magazines.

C. They gave information  about themselves.

D. They are teenage boys

A. You won’t be able to visit the USA if you have a visa.

B. You could visit the USA if you didn’t have a visa.

C. If you don’t have a visa, you can’t visit the USA.

A. Unless we were staying in the same hotel, we could share a room.

B. If we stay in the same hotel, we could share a room.

C. If we were staying in the same hotel, we could share a room.

A. intend

B. intends

C. are intending

C. are intending

A. She had learned English for five years after she went to London.

B. Before she had went to London, she learned English for five years.

C. She had learned English for five years before she went to London.

D. She learned English for five years before she went to London.