l'm doing my homework.(be后面动词用现在进行时态)固定用法
They need to work hard.(to后面动词一律用原型）固定用法
What colour do you like?有动词like了,不能再用系动词,又是特殊疑问句,所以用do.
The cat is beside the ball.（between,两个物体者之间,猫不能在墙之间,只能在旁边
Can I have some cakes?第一人称用动词原形,第三人单数才用has