无线电兴趣小组的同学，用电烙铁将零件焊在线路板上，在焊接过程中焊锡发生的物态变化有 ．
熔化和凝固
人力推车只能在水平巷道，巷道坡度不得超过（），一人只能推一辆车。
A.3‰
B.5‰
C.6‰
D.7‰
The American basketball team announced that they would not ______ first place to any team.
A．yoke B．yell C．yield D．yearn
