Why do people build zoos— they can help those animals in danger.

Look at the naughty boy! You ______ have taught him how to behave himself.

I can’t do the work by myself so I ________ a student to help me.

The doctors has_________ a new idea on the treatment, which is well thought of by his companions.

I’d like to buy a house — modern, comfortable, and ____ in a quiet neighborhood.