be doing sth.when
be doing sth.when
如何对be doing sth when造句
be on the point of doing sth.when...
be always doing sth .
用 Sb who do sth be like sb else doing sth else who,when/once
be worried doing sth 还是be worried about doing sth
be successful in (doing) sth.be successful at (doing) sth.
be worth sth./doing sth.造句,
be worthy of sth / doing sth.
be busy doing sth/with sth
be interested in doing sth
be used to doing sth?