Sometimes Daniel walks for half ________ hour to the zoo.

Peter, what’s your mother doing now?—She____________in the kitchen.

Every time Ashtita tries to break a record, he reaches a point ______ he feels he cannot physically do any more.

Look at the glasses on the desk. Are they David’s?—They belong to him. I saw him go out with glasses just now.

scientists have done a lot of research on A (H1N1) flu, there are still some cases for further study.[ ]