. According to some doctors, one of the ways to prevent us from growing old is to make sure that our brains get enough___.
Keep me _____of the latest news.
As a young man, Comrade Zhou Enlai ________ the students' movements and later ________ the Communist Party of China.
The questions which are ________ to yours are not easy to answer.
There must be ________ with the computer.
About six months later,the letter they were looking forward to ________at last.