Having lived in China for 8 years, Helen has a good ________ of both English and Chinese.

He _____ to us that those eggs which were _____ on the table had been _____ by snakes.[ ]

As we know, the coming of radio in this century made ocean sailing much ______.

Alone we can do so little, together we can do so .

Mr Li began to teach in this school, _______, some time later, she became popular with the teachers and students for her excellent teaching levels.