Won't you come in and take a seat?你不进来坐一下么 Will you come in and take a seat?你愿意进来坐一下么?两句话都是表达邀请的意思.第一句话的情况可能是被邀请的对象准备走了,略表疑问；
He said I could borrow his bike.和 He said that I might borrow his DVD.两句话都是宾语从句,that都可以省略.句子意思不变.
He ought not to have done so even if possible.即使有可能,他也不应该这么做.