题干
Studying in groups is necessary __________ you want to do well in school.
A：if
B：until
C：unless
D：though
答案(点此获取答案解析）
A
Studying in groups is necessary __________ you want to do well in school.
A：if
B：until
C：unless
D：though
，若
且
，则下列结论中必成立的是（ ）
