21．We’ve had a good start, but next, more work needs _____to achieve the final success.
A．being done B．do C．to be done D．to do
22．Sharon ______ in a big city for many years, but she is now content to live in the countryside.
A．lived B．was living C．has lived D．had lived
23．Time, ________ correctly, is money in the bank.
A．to use B．used C．using D．use
