写出下列反应的离子方程式
(1)锌与稀硫酸反应
(2)用石灰石与盐酸反应制取二氧化碳:
As a new graduate, he doesn't know ___________ it takes to start a business in his hometown. [ ]
A. how
B. when
C. what
D. which
图甲电路中交流电源电压随时间的变化规律如图乙所示.若电阻为R=100Ω,则理想电流表和电压表的示数分别为( )
A.1.41A 200V
B.1.41A 141V
C.2A 200V
D.2A 141V