【題目】19世紀末，物理學家瑞利在研究中發(fā)現(xiàn)，從空氣中分離得到的氮氣密度，與從含氮物質(zhì)制得的氮氣密度有0.0064 kg/m3的差異，他沒有放過這一發(fā)現(xiàn)，在化學家拉姆塞的合作下，經(jīng)過十幾年的努力，于1894年發(fā)現(xiàn)了空氣中的氬氣。下列說法正確的是________(填序號)。

①氬是一種化學性質(zhì)極不活潑的氣體；

②瑞利從空氣中分離的氮氣是純凈物；

③19世紀末以前，人們認為空氣由氧氣和氮氣組成的；

④瑞利發(fā)現(xiàn)，從含氮物質(zhì)制得的氮氣密度大于從空氣中分離的氮氣的密度。

【題目】空氣的主要成分①氧氣、②氮氣、③稀有氣體、④二氧化碳及其他氣體雜質(zhì)，按體積分數(shù)由大到小的順序排列正確的是(　　)。

A. ①②③④ B. ②①③④

C. ①②④③ D. ②①④③

【題目】下列關于空氣成分的敘述正確的是( )。

A．空氣中氮氣和氧氣的體積比約為4∶1

B．空氣的成分按質(zhì)量計算，氮氣占78%，氧氣占21%

C．從液態(tài)空氣中能分離出氮氣，不能分離出氧氣和稀有氣體

D．空氣中含量最多且性質(zhì)又不活潑的是稀有氣體

【題目】My uncle likes sports very much. He loves soccer ball, basketball, baseball, tennis and more. He plays baseball and basketball very well. He likes to watch the sports games on TV. He plays sports every day. He has a small(小的) sports collection. He has 3 tennis rackets, 2 baseballs, 3 basketballs and a soccer ball.

根據(jù)短文內(nèi)容判斷正(T)誤(F)。

【1】My uncle doesn’t like sports, but he has a sports collection.

【2】He plays baseball and basketball very well.

【3】He likes to watch the sports collection on TV.

【4】He watches TV and plays sports every day.

【5】His collection is small: 3 tennis rackets, 2 baseballs, 3 basketballs and a soccer ball.

【題目】I am an American boy. ___name is Paul. I am 12 . I___two friends, Sally and Mona. They’re___. We play sports___. We play soccer, basketball, volleyball and____ Sally___a sports collection（收藏）.___has seven soccer balls,___basketball, four volleyballs, and six tennis rackets. We often(經(jīng)常)___volleyball on TV. What sports____you often play?

【1】A. My B. His C. Her

【2】A. am B. do C. have

【3】A. them B. brothers C. sisters

【4】A. everyday B. every day C. morning

【5】A. sports B. more C. them

【6】A. doesn’t have B. plays C. has

【7】A. He B. She C. Paul

【8】A. one B. zero C. three

【9】A. play B. have C. watch

【10】A. do B. does C. don’t

【題目】

【1】a，v,e,h, _____

【2】e,t,n,n,s,i _______

【3】l,b,a,v,o,l,y,e, l,l________

【4】u,f,n ______

【5】o,u,s,n,d ______

【6】a,c,s,s,l _______

【7】a,e,l,t_____

【8】e,s,a,m_______

【9】i,w,h,t ________

【10】b,o,i,n,r,g_______

【題目】–Let’s play computer games. - _______.

A. Yes, we do B. No, we don’t C. That sounds good.

【題目】下列物質(zhì)中屬于混合物的是( )。

A．氮氣 B．二氧化碳

C．空氣 D．氧氣

【題目】有兩個集氣瓶，分別充滿空氣和氮氣，試用簡單的方法加以鑒別。

________________________________________________________________________。

【題目】下列事例中，能增大壓強的是（ ）

A、把書包帶做得寬些 B、在坦克的輪子上安裝履帶

C、刀、斧、剪的刃磨得很薄 D、在鐵路的鋼軌下鋪上枕木