受要约人在承诺期限内发出承诺，按照通常情形能够及时到达要约人，但因其他原因承诺到达要约人时超过承诺期限，此时，承诺的效力如何？（）

A.有效

B.无效

C.成为新要约

D.除要约人及时通知受要约人因承诺超过期限不接受该承诺的以外，该承诺有效

It is said that about ______of the books and magazines in the world______in English.

A. four-fifths;are written      B fourth fives;are written

C, four fifth;were written      D fourth fifths; were written