英国加入欧共体的障碍不包括()
A、联邦问题
B、农业税问题
C、法国的阻碍
D、国内反对
参考答案:D
-I think _______ask Tim for some advice.
-_______. Last time when I turned to him, he refused to help.
A.you'd rather; I think so
B.you'd better; I'd rather not
C.you have to; I'd rather not
D.you'd better; I think so
作如下改变时,分别画出直流他励电动机的人为机械特性(n-T曲线),并说明其变化特点: ①电枢回路中串接附加电阻时(Rad=0及Rad1<Rad2<Rad3); ②改变电枢电压时(UN>U1>U2>U3); ③改变磁通时(ФN>Ф1>Ф2>Ф3)。