We must keep a secret of the things_______ here", the general said,　_______ at the man in charge of the information office

Please ____me at chinalin@sina.com.

It was in the school ___ he studied ten years ago ____ he gave a wonderful speech.

To understand the grammar of the sentence, you must break it ____into parts

The group of students went to the suburb, did some research work, and ________ the water in the river to see if it had been polluted.[ ]