need sth doing是某物需要什么
如The meat need cutting
sb need to do是某人需要干什么
如I need to ask my teacher for answer
至于be supposed to do和be supposed to be doing
是时态不同
be supposed to do是一般现在时
be supposed to be doing
是现在进行时 need sth doing是某物需要什么
如The meat need cutting
sb need to do是某人需要干什么
如I need to ask my teacher for answer
至于be supposed to do和be supposed to be doing
是时态不同
be supposed to do是一般现在时
be supposed to be doing
是现在进行时