蔷薇科分为哪几个亚科？写出每个亚科的区别。

如图所示，质量不计的轻质弹性杆P插入桌面上的小孔中，杆的另一端套有一个质量为m的小球，今使小球在水平面内作半径为R的匀速圆周运动，且角速度为ω，则杆的上端受到球对其作用力的大小为（  ）

A．mω²R

B．

C．

D．不能确定

Middle born children will tell you that they usually didn’t feel all that special while growing up. The first born had his spot-carrier of the family banner and responsible for everything. The last born had his comfy little role, but the middle born had no distinctive place to call his own.

Middle-borns just seem to be easily overlooked, and maybe that’s why there are so few pictures of them in the family photo album. There may be hundreds, seemingly thousands, of pictures of the firstborn. For some strange reason, however, which I have confirmed by polling middle-born children around the world, there are seldom many pictures of the middle child, and what photos there are have him included with the others -- squeezed again between the older sibling and the younger sibling.

Another thing that can be said of many middle-born children is that they typically place great importance on their peer group. The middle child is well known for going outside the home to make friends faster than anybody else in the family. When a child feels like a fifth wheel at home, friends become very important; as a result, many middle children (but not all, of course) tend to be the social lions of the family. While firstborns, typically, have fewer friends, middle children often have many.

Middle children have a propensity to leave home first and live farther away from the family than anyone else. I observed a dramatic illustration of this tendency while I was a guest on Oprah Winfrey’s show. The subject that day was sibling rivalry. Three charming young women, all sisters, were among the guests, and we quickly learned that the firstborn and the last born were residents of the Eastern state where they had grown up. They had settled down near their parents and other family members. But the middle child had moved to the West Coast.

I suppose she could have gotten another two thousand miles farther away by moving to Hawaii, but her point was still well made. Middle children are the ones who will most often physically distance themselves from the rest of the family. It’s not necessarily because they’re on the outs with everyone else. They simply !ike to do their own thing, make their own friends, and live their own lives.

All of this is not to say that middle children totally ignore their siblings or the rest of the family. one common characteristic of the middle child is that she is a good mediator or negotiator. She comes naturally into this role because she’s often right in the middle, between big brother and little sister, whatever the case may be. And because she can’t have Mom or Dad all to herself, she learns the fine art of compromise. Obviously, these skills are assets in adult life, and middle children often become the best adjusted adults in the family.

How did the author get to know that middle children have fewer pictures in the family photo album？（）

A．Form the complaints of middle children.

B．Form his own family situation.

C．By asking a lot of middle children.

D．By going to Oprah Winfrey’s show.

对预防恶性高热的发生，作用不大的是（）

A.了解有关的家族遗传史

B.对可疑病人做肌肉收缩试验

C.加强心肺功能

D.测定血浆CPK含量

E.密切监测麻醉病人体温变化

在超市购物后，李平把七件商品放在超市的传送带上，肉松后面紧跟着蛋糕，酸奶后面接着放的是饼干，可口可乐汽水紧跟在水果汁后面，方便面后面紧跟着酸奶，肉松和饼干之间有两件商品，方便面和水果汁之间有两件商品，最后放上去的是一只蛋糕。

如果上述陈述为真，那么，以下哪项也为真？（）

Ⅰ．水果汁在倒数第三位置上。

Ⅱ．酸奶放在第二。

Ⅲ．可口可乐汽水放在中间。

A．只有Ⅰ。

B．只有Ⅱ。

C．只有Ⅰ和Ⅱ。

D．只有Ⅰ和Ⅲ。

王某因多次行窃被公安机关处以15日行政拘留，王某不服向复议机关申请复议，复议机关维持了原行政处罚。王某以复议机关为被告向法院提起行政诉讼。法院的下列做法正确的是（）。

A.以被告不适格为由驳回起诉

B.以被告不适格为由变更被告，将作出原具体行政行为的公安机关列为被告

C.以被告不适格为由，通知王某变更被告

D.通知作出原具体行政行为的公安机关作为第三人参加诉讼