Itisbelievedthatanewkindofdrug

問題詳情：

It is believed that a new kind of drug _____ by the scientists and they are hopeful that they will succeed in a few months.

A. has been developed                 B. is being developed

C. is developing                        D. has developed

【回答】

B

知識點：現在進行時及其被動式

題型：選擇題