螺纹的主要参数有公称直径、（）、线数、导程、旋合长度等。A.牙型 B.螺距 C.旋向

骨质疏松症最常见的症状是（）

A.腰背痛

B.发热

C.骨折

D.行走困难

E.乏力

根据短文内容，从短文后的选项中选出能填入空白处的最佳选项。选项中有两项为多余选项。

The right pair of exercise shoes can do a lot to prevent discomfort and injuries, personal trainers say．Here are some shopping tips:

­    小题1:   Depending on your workout, shoes designed for walking, running, tennis, cross-training or another specialty will provide the best support for your feet．

Shop when you normally exercise．Feet actually get bigger throughout the day, sometimes swelling up as much as a half-size by nighttime．  小题2:  

Try them on．Never grab a pair of exercise shoes based only on the size of footwear you normally buy．Bring the type of socks you’d wear to work out and go for a walk through the store．

  小题3:   You should be able to spread your toes out comfortably．Make sure there’s about a half-inch of space between them and the front of the shoe．The back should fit snugly (warmly and comfortably) against your heel and not move up and down．If your feet are different sizes, buy based on the larger one．

Talk to an expert．Shoe salesmen and personal trainers can study your stride (步伐) and the shape of your feet． 小题4:  

  小题5:  Many trainers recommend switching footwear every three to five months, if possible, to maintain（保持）proper cushioning and support．

One tip: if you have to tie your shoes very tightly to feel a good amount of support, they may be ready to go．

A．Think about how much you can afford to buy the workout shoes．

B．Consider your type of exercise．

C．Focus on fit．

D．So don’t shop first thing in the morning if you often work out in the evening． E．Pay more attention to new style shoes．

F．Replace worn shoes regularly．

G．Usually they can recommend the best shoes to guard against injuries．

居民甲有两套住房，将其中一套住房出售给居民乙，成交价格为200万元，将另一套住房与居民丙交换，换得一套三室两厅两卫住房。同时，居民甲向居民丙支付差价款100万元。此后，居民甲将此三室两厅两卫住房出租给居民丁居住，2009年全年租金为5万元(与市场租金水平相当)，居民丙取得房屋后，将此房屋等价交换给居民丙的同事。(假设该省规定按房产原值一次扣除30%后的余值计税，契税税率为3%)

甲出租房屋应缴纳的房产税为（）万元。

A．0

B．0.2

C．0.3

D．0.6

汽车的动力性能指标有哪些？

胃十二指肠溃疡引起大出血的原因是()。

A．胃十二指肠壁微血管不断渗血

B．溃疡侵及胰腺引起大出血

C．溃疡基底的动脉被侵蚀破裂

D．胃窦部黏膜炎性糜粒渗血

E．胃酸作用使渗血不易凝固