按要求完成下列各题。(20分)
（1）These are tiger_cubs．(就画线部分提问)
________ are these?
（2）They are lion cubs.(改为一般疑问句)
________ ________ lion cubs?
（3）The bear can ride a bike.(改为否定句)
The bear ________ ride a bike.
（4）Are those lions?  (作肯定回答)
________，________ ________．
（5）What is this? (改为复数句)
What ________ ________？