A:有顺时针方向的电流且有收缩的趋势
B:有顺时针方向的电流且有扩张的趋势
C:有逆时针方向的电流且有收缩的趋势
D:有逆时针方向的电流且有扩张的趋势
银杏种子外有肉质的果皮,所以属于被子植物.(判断对错)
—Must I hand in my homework today? —No, you ______ .