【题目】 CT is really useful invention, with which doctors can find out what's wrong with a patient more easily.
A. A; a B. The; an C. The; a D.A ;the
在线课程【答案】C
【解析】句意：CT是一种有用的发明，医生可以依靠它很容易地找到病人哪里出毛病了。指科技发明一般用定冠词the；一种有用的发明，应用不定冠词，useful以辅音音素/j/开头，故用a。故选C。