锅炉给水温度降低、燃料量增加，使发电煤耗（）。
参考答案：提高
Java本身的编译器用 ______ 语言编写，运行系统的虚拟机用 ______ 语言实现，这样Java系统本身也具有可移植性。
I called Mary many times yesterday evening. But I couldn’t get through. Her brother _____ on the phone all the time.
A．talked
B．had talked
C．has talked
D．was talking
