单选题
Between 1890 and 1970 the monetary costs of supplying energy _____ more or less constant or declined.
A、
to stay
B、
was stayed
C、
stayed
D、
has stayed
【正确答案】
C
【答案解析】
Between 1890 and 1970 是过去的时间短，因此用过去式。c. stayed
提交答案
关闭