heat changes water into steam-科学事实用一般现在时
under the direcion of our teacher,we have made great progress recently
his family is going to have a long journey -family作为一个家庭讲是单数
l can't bear your playing basketball on the playground-bear后面接动名词
my mother tried to compose herself-try与 make an effort 重复
have you ever been here?and if have how many times?-来过这里才能接着问来了几次
as is known to us,great changes have taken placein China-as is known to us的用法