不能在机器过载时防止重要零件损坏的传动方式是（）
A．带传动
B．摩擦轮传动
C．液力传动
D．蜗轮蜗杆传动
参考答案：D
To meet the need of the London Olympic Games in 2012， many new stadiums are reported to________ in Britain.
A．held；be constructed
B．to be held；have constructed
C．to be held；be being constructed
D．to be held；be constructing
内部报酬率
