A.低速擋 B.中速擋 C.高速擋
A.質(zhì)量大,熱膨脹系數(shù)小 B.質(zhì)量小,熱膨脹系數(shù)大 C.慣性力小,熱膨脹系數(shù)小 D.質(zhì)量小,慣性力大
A.1 B.1.5 C.2 D.2.5