______ trees are planted each year on the Tree-planting Day all over the country.

A. Tens of thousands of B. Tens and thousands　　　　

C. Ten of thousands of　　　　　　　　　　　　　　　　　　 D. Tens of thousand

________ trees are planted each year on the Tree-Planting Day all over the country．

1. A.
   Tens of thousand
2. B.
   Tens of thousands of
3. C.
   Tens and thousands
4. D.
   Ten of thousands of

_____ trees are planted each year on the Tree-Planting Day all over the country.

　 A.Tens of thousand　　 B. Tens of thousands of

　 C.Ten of thousands of D. Tens and thousands