1. He kept his head _____ water when he began to learn swimming, but he raised his head now and then
A. over B. below C. above D. up
2. Another grand bridge will be built _____ the Pearl River in our city.
A. along B. up C. on D. across
3. I'll leave Beijing for Guangzhou ____ a week, while my brother will leave Guangzhou for Beijing ____ our National Day.
A. in, in B. after, in C. after, after D. in, after
