used to do

1、used to do 过去常常(表示现在不再) used to do过去常常，过去曾经;过去常常做某事He used to do his homework on Sunday, but now he often does homework on Saturday.他过去在星期天做家庭作业，但是现在他经常在星期六做作业。 2、eg: I used to swim in the lake...

1.基本用法特点 used to的意思是“过去经常”，其中的to是不定式符号，不是介词，所以其后接动词原形(不接动名词)。如： He used to live in Paris. 他过去一直住在巴黎。 2.Be used to do sth. 被用来做某事 例句：Wood is often used to make furnitures. 3.Be used to doing sth,...

这是两个完全不同的短语，used to do sth意为过去常常做某事，表示过去的动作或状态，含有现在也不那样做了。如： i used to run around the park, but now i like playing basketball. be worth to do sth是不正确的表达，正确是be worth doing sth.值得做某事...