difficult是加动词ing?还是加to do sth.

difficult是加动词ing?还是加to do sth. let's 是加动词ing 还是加动词原形? rather than之间 动词是原形还是动词加ing? love后边的动词+ING吗love后边的动词是加to还是加“ing”about后边的动词是加to还是加“ing” was+动词ing还是加动词过去式? study加动词ing还是动词不定式 should 后面是加动词原形还是ing形式 do well in后面是加动词原形还是ing he is后动词是加ing还是S为什么? thanks to 后面的动词是原形还是加ing still后面加动词什么结构?是原型还是ING? favourite后面加动词ing形式还是加动词原形? be going to 加动词ing 还是动词加S? 请问used to是加动词ing还是加动词原型 you had better 是后面加动词ing形式或者加动词原形还是加to在动词前? 祈使句后面加动词ing,还是原型? forget 加动词ing还是原形 practice后面加不定式还是动词ing