机车运行中,联合调节器工作不稳定使柴油机游车,导致柴油机功率()。
A.过大
B.不足
C.不稳
参考答案:C
All that can be done ____.
A.has been done
B.have been done
C.have done
D.has done
1,4,7,10,( )
A.14
B.13
C.15
D.21