Question

---We can't be successful _____  we keep on working hard.
---I agree with you.

A．if

B．because

C．unless

D．until

Answer 1

C

連詞unless意為“除非……如果不……”，“除了……”，多引導(dǎo)一個(gè)否定意義的真實(shí)條件句，有時(shí)也可引導(dǎo)非真實(shí)條件句。