为确保铲车经济性,当最低运距一般在()km以上时,装载机须用其他车辆牵引到现场。
A、1000
B、20
C、3000
D、5000
参考答案:B
选词填空。
1. (Does, Did) you bring gifts?
2. (It's, It) Christmas morning.
3. (Whose, Who) brings these flowers?
4. The box (have, has) her name (in, on).
5. We open the gifts (quick, quickly).
6. He (give, gives) his gift (to, with) his parents.
T细胞活化时只有第一信号,缺乏第二信号,其结果将导致
A.T细胞分裂
B.T细胞分化
C.T细胞处于克隆无能状态
D.T细胞克隆扩增
E.以上部不是