从A、B、C、D四个选项中，选出可以填入空白处的最佳选项，并在答题卡上将该项涂黑。
21. –I find Chinese people are helpful when traveling around China.
–You’re right. I like ______ when people are friendly and helpful.
A. that B. them C. one D. it
22. –If you can wait for a moment, I can help you with the problem.
–Thank you for offering help, but I think I can _______ it.
A. do B. make C. try D. manage
23. When a new disease breaks out, experts must ________ what to do in the fastest way.
