组合钢模板中，代号8120表示（）。
A、平面模板
B、阳角模板
C、阴角模板
D、固定角模
参考答案：C
-I went to see you yesterday evening. But you weren't in. Where were you then?
-I _________ a walk by the lake with my husband.[ ]
A. was having
B. am having
C. have had
D. have
在一般情况下，上溶速度约为侧溶速度的4倍，底溶速度最低，因为溶洞底浓度高，而且盐类矿石表面覆盖了不溶物，阻碍矿石溶解所致。（）
