我国已将（）采煤机作为今后的发展方向。
A、机械牵引
B、液压牵引
C、电牵引
D、链牵引
参考答案：C
电流从高电势点流向低电势点时，电场做正功，电流从低电势点流向高电势点时，电源做正功
Assuming that a company's ROE is 12% and the required rate of return is 10%, which of the following would most likely cause the company's P/E ratio to rise（）
A. The inflation rate falls.
B. The firm's dividend payout rises.
C. The firm's ROE falls.
