_______ many times, he finally understood it．
A．Taught B．Teaching C．Having taught D．Having been taught
Ladies and gentlemen, please remain ________ until the plane has come to a complete stop．
A．seated B．seating C．to seat D．seat
He told us whether _________ a picnic was still under discussion．
A．to have B．having C．have D．had
--Has your teacher returned from America yet?
--Yes, but he _______ here for only three days before his company sent him to Africa．
A．was B．has been C．will be D．would be
It is said that he will______ his uncle’s business when he is mature enough to deal with the pubic relations．
A．think over B．hand over C．take over D．go over
Jack’s family _______ their holiday in Shanghai this time next week．
A．are enjoying B．are to enjoy
C．will enjoy D．will be enjoying
