题干

_________ of my parents was at home last Sunday. So I _________ cook by myself.

A:Neither, have to

B:Either, have to 

C:Neither, had to

D:Either, had to

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C

同类题1

(Ⅰ)气体制备时须先检查装置的气密性,下列各图所示装置,肯定不符合气密性检查要求的是  ____ .

(Ⅱ)下面是中学化学实验中常见的几种仪器:

a.量筒    b.容量瓶    c.分液漏斗    d.托盘天平   e.温度计

(1)其中标示出仪器使用温度的是 ____(填编号).

(2)称取10.5g固体样品(1g以下使用游码)时,将样品放在了天平的右盘,则所称样品的实际质量为  ____ g.

(3)使用前要检查仪器是否漏液的是  ____(填编号).

(Ⅲ)实验室需要95mL 1.0mol•L1稀硫酸,现用98%的浓硫酸(其密度为1.84g/mL)来进行配制.若实验仪器有:

A.100mL量筒       B.托盘天平          C.玻璃棒         D.250mL容量瓶

E.10mL量筒         F.胶头滴管        G.50mL烧杯    H.100mL容量瓶

(1)需量取浓硫酸的体积为  ____ mL.

(2)实验时选用的仪器有(填序号)  ____

(3)配制过程中,下列情况会使配制结果偏高的是(填序号)  ____

A.将稀释的硫酸液转移至容量瓶后,未洗涤烧杯和玻璃棒.

B.将烧杯内的稀硫酸向容量瓶中转移时,因操作不当使部分稀硫酸溅出瓶外.

C.未冷却至室温就定容.

D.用胶头滴管加水时,俯视观察溶液凹液面与容量瓶刻度相切.

E.容量瓶使用时未干燥

F.定容后经振荡、摇匀、静置,发现液面低于刻度线,再加蒸馏水补至刻度线.

同类题5

完形填空

    Imagine loving someone so much that you'd swim more than 5, 000 miles to see him or her. Dindim manages to swim that far every year to 1 his friend Joao. This is 2 not only because of the love between the two friends, but because Dindim is3a penguin. Joao found Dindim covered in oil, barely 4on a beach near his home. He picked him up, cleaned him off and brought him to his house where he 5 him and got him healthy again. Joao named him Dindim.

    After a week, he 6 the penguin back to the beach and tried to release him,7 Dindim refused to leave Joao. They 8 together for the next eleven months. Then, Dindim disappeared.9 Joao thought he'd never see his friend again. But just a few months 10 Dindim was back. He found Joao on the beach, and followed him home. Each year he 11four months to live with other penguins. For the other eight months, he lives with Joao. Joao says that each time they meet again, Dindim seems 12 to see him. He says he loves the penguin as if he were his own 13 He feels certain that Dindim loves him in the14way. Ecologist Carl Safina says that animals can and do love humans. He writes and speaks a lot about animals and their 15. According to Carl, it's obvious that animals feel love for humans. What's less obvious is whether or not humans love animals enough to 16 them. Hundreds of thousands of animals are 17 by the same oil that covered Dindim when Joao found him.

    Fifty percent of 18 has disappeared in the last 40 years because of humans'19 their habitats. Scientists say we're in a new mass extinction period. In the next two 20 they predict that we'll lose 75 percent of the remaining species on earth.