题干
--- How do you study ______ a test?
--- I study ______ working with a group.
--- I study ______ working with a group.
A：for, by
B：by, i
C：for, from
D：by, for
答案(点此获取答案解析）
A
。当变压器工作时原、副线圈中：
的解集是（ ）。