She looked up and nodded for me ______..
A.to come in
B.coming in
C.came in
D.come in
答案:A
用多用电表测直流电压U和测电阻R时,若红表笔插入多用表的(+)插孔,则[ ]
A.测U时电流从红表笔流入多用表
B.测U时电流从红表笔流出多用表
C.测R时电流从红表笔流入多用表
D.测时R电流从红表笔流出多用表