只要改变电磁转差离合器励磁绕组中的励磁电流，就能调节离合器的输出转矩和转速。
参考答案：对
After driving all night we got to Amy’s place，_____ that she was away.
A．only to discover
B．only discovering
C．only discovered
D．only having discovered
小明在维修铁栅栏门时需要一节细钢管，下面工具中适合截取、加工这段钢管的工具是（）
A.①③⑥
B.③④⑥
C.①③④
D.②⑤⑥
