It's our duty _______ our classroom clean and tidy.
A:keep
B:to keep
C:keeping
D:kept
Yao Ming was a great basketball player. I like _______ very much.
1.2平方米=____平方分米.
1.2立方米=____立方分米.
7120立方厘米=____立方分米.
4.4立方分米=____立方分米____立方厘米.
10立方米80立方分米=____立方米.
— These problems are too hard to . Will you give me some advice? — There are many ways. The most important is to have a careful plan.