弯制口外弓的外弓用
A.1.4~1.6mm钢丝
B.1.0~1.2mm钢丝
C.1.4mm以下均可
D.1.2~1.4mm钢丝
E.0.9~1.0mm钢丝
参考答案:A
Bill was doing a lot of physical exercise to build up his________.[ ]
A. ability
B. force
C. strength
D. mind
下列现象中属于化学变化的是( )
A.矿石粉碎
B.铁制成铁锅
C.煤气燃烧
D.冰块融化