—Not really. She ___us clear directions and we were able to find it easily?
A:was to give
B:had given
C:was giving
D:would give
写出一条造成水资源严重污染的原因____
如图所示,甲、乙两同学从河中O点出发,分别沿直线游到A点和B点,AO、OB分别于水流方向平行、垂直,且OA=OB.若水流速度不变,两人在靜水中游速相等,则他们所用时间t甲、t乙的大小关系为( )