We should pay more attention ______teenage problems.
| A．at | B．to | C．in | D．On |
______he was exercising at the park yesterday morning, he found a purse under the tree.
| A．While | B．Before | C．Though | D．If |
There is ______ university in the east of the city and ______ university is big and modern.
| A．a; the | B．the; a | C．the; an | D．an; the |
—Mom, this is my friend, David. — .
| A．I don't know | B．Nice to meet you |
| C．You're good | D．Here you are |
Let’s play ____ basketball.
| A． / | B．the | C． a | D．an |