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 ________ ________?