下图为焊锡熔解的方法，（）是不允许的。
A.a
B.b
C.c
D.a及c
参考答案：B
TV-Turnoff Week, _______ millions of people around the world participate every year, tries to encourage people to turn on life.
A．in which
B．on which
C．which
D．when
LKJ-2000型显示器显示内容及格式是什么？
