The authorities _______ actions to stop illegal purchase of wild animals and their associated products effectively. However, they didn’t do so.

A. must have taken B. had to take C. needed have taken D. should have taken

Pumpkin seeds, _______ protein and iron, are a popular snack.

A. that B. provide C. which D. which provide

 _______ the distance was too far and the time was short, we decided to fly there instead of going there by train.

A. To discover B. Discovered C. To have discovered D. Discovering

They'll be able to walk across the river _______.

A. if the ice is thick enough

B. if the ice will be thick enough

C. when the ice will be thick enough

D. unless the ice is thick enough

Although he is my friend, I find it hard to _______ his selfishness

A. put up with B. catch up with C. keep up with D. come down with

Some economists argue that new technology cause unemployment. Others feel that it allows more jobs to be created

A. Some economists argue that new technology causes unemployment, so others feel that it allows more jobs to be created

B. Arguing that new technology causes unemployment, other economists feel that it allows more jobs to be created

C. Besides the argument that new technology causes unemployment, some economists feel that it allows more jobs to be created

D. Some economists argue that new technology causes unemployment whereas others feel that it allows more jobs to be created

Our products are environmentally- friendly. We package all of them in recyclable materials.

A. Packing our products in recyclable materials, we made them environmentally - friendly.

B. Our products are packaged in recycled materials to be environmentally-friendly.

C. The recyclable package of our products makes them look environmentally-friendly.

D. Packed in recyclable materials, our products are environmentally-friendly.

It was careless of you to leave the windows open last night.

A. You shouldn’t leave the windows open last night.

B. You are so careless that you left the windows open last night.

C. You shouldn’t have left the windows open last night.

D. You might have been careless because you left the windows open last night.

They advised locking the doors carefully at night

A. They advised that the doors should be locked carefully at night.

B. The doors were advised to be locked carefully at night.

C. They advised the doors being locked carefully at night.

D. They advised to lock the doors carefully at night.

We couldn't solve the problem until our teacher arrived

A. Not until we solved the problem could our teacher arrive.

B. When our teacher arrived, we solved the problem.

C. Until our teacher arrived, we were able to solve the problem.

D. Not until our teacher arrived could we solve the problem.