Pieces of bamboo or wood ________ books between 2nd and 5th century AD.A. used to formed B. used to formC. were used to form D. used to beforming
The picture _______ on the wall is painted by my nephew.
_______ the general state of his health, it may take him a while to recover from the operation.
In order to gain a bigger share in the international market, many state-run companies are striving _______ their products more competitive.
Fishing is his favorite hobby, and _______.
There are five pairs _______, but I’m at a loss which to choose.