23.Whatisthewoman'sdreamvacationlike?
A nice trip to Chicago and Europe.
B.Aweekaloneatahotspringresort.
C.Comfortabledaysathigh-classaccommodations.
D.Quietnightswithbrightstarsandabluemoon.
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24. Why does the woman want a new kitchen stove?
A.Theoldonedoesn'twork.
B.Theoldoneburnsthewoman'smeals.
C.Theoldoneistoosmallforthefamily.
D.Theoldonealwaysleaksgas.
25.Whatdoesthewomansuggestdoingbeforetheyplanthetrip?
A.Talkingwithfriendsaboutthetrip.
B. Having lunch quickly.
C.Buyingsometravelbooks.
D.Checkingtheircaratthegarage.
如果作用在径向轴颈上的外力加大,那么轴颈上摩擦圆( )。
A. 变大;
B. 变小;
C. 不变
D. 变大或不变。
在考虑摩擦时,运动中的转动副上,约束反力的作用线()
A. 与转动副相切
B. 与摩擦圆相切
C. 与转动副相交
D. 与摩擦圆相交