题干
People more chances to receive good health care than they used to, and they're living longer as a result.
A：will have
B：have
C：had
D：were having
答案(点此获取答案解析）
B
， 物块与木板间动摩擦因数为
， 已知木板始终处于静止状态， 那么下列说法正确的是（ ）
