在SDH传输体制中，国际电联（ITU-T）G.709建议规定了（）种标准容器。
A.4
B.5
C.8
D.10
参考答案：B
It seems as if she has forgotten all about her ambition now she made it hers to make a bit of progress every day when school started.
A．while
B．despite
C．though
D．unless
电动机应设有：短路、（）、（）三种保护。
