现在给出1、2、3、…、11、12这12个数,在其中某些数前面添加负号后,使这1

题型:填空题

问题:

现在给出1、2、3、、11、12这12个数,在其中某些数前面添加负号后,使这12个数的和为0,写出一个你认为正确的式子(    ).

考点:有理数的加减混合运算
题型:填空题

对结核菌描述正确的是

A.不产生内毒素和外毒素

B.只产生内毒素

C.有荚膜,有鞭毛

D.产生侵袭酶

E.肺外感染可发生在腹膜,不会发生在肠道

题型:填空题

Play is the basic business of childhood, and in recent years more and more research has shown the great importance of play in the development of a human being. From earliest  infancy (婴儿), every child needs opportunity and the right material for play, and the main tools of play are toys. The main function of toys is to suggest, encourage and assist play. To succeed in this, they must be good toys, which children will play with often and will come back to again and again. Therefore, it is important to choose suitable toys for different stages of a child’s development.

In recent years research on infant development has shown that the standard a child is likely to reach, within the range of his inherited(遗传的) abilities, is largely determined in the first three years of his life. So a baby's ability to benefit from the right play materials should not be underestimated. A baby who is encouraged, talked to and shown things and played with, has the best chance of growing up successfully.

The next stage, from three to five years old, curiosity knows no bounds. Every type of suitable toy should be made available to the child, for trying out, experimenting and learning, for discovering his own particular ability. Bricks and jigsaws and construction toys; painting, scribbling(乱涂) and making things; sand and water play; toys for imaginative and pretending play; the first social games for learning to play and get on with others.

By the third stage of play development—from five to seven or eight years old— the child is at school. But for a few more years play is still the best way of learning, at home or at school. It is easier to see which type of toys the child most enjoys.

Until the age of seven or eight, play and work mean much the same to a child. But once reading has been mastered, then books and school become the main source of learning. Toys are still interesting and valuable, which lead up to new hobbies, but their significance has changed —to a child of nine or ten years old, toys and games mean, as to adults, relaxation and fun.

小题1:The writer wants us to understand that a child_______.

A.cannot grow up without toys

B.matures(使成熟) through play

C.uses toys as friends

D.has to be taught how to play小题2:According to the passage, the abilities a child has inherited from his parents ________.

A.determine his character

B.will not change after the age of three

C.partly determine the standard he is likely to reach

D.to a large extent determine the choice of toys小题3:The passage tells us that children are the most curious when they are about______.

A.two years old

B.one year old

C.six years old

D.four years old小题4:The article is about_______.

A.the importance of play

B.the importance of books

C.the relationship between play and work

D.children’s speech development

题型:填空题

如图甲所示为半圆形的玻璃砖,C为AB的中点。a、b两束不同频率的单色可见细光束垂直AB边从空气射入玻璃砖,且两束光在AB面上入射点到C点的距离相等,两束光折射后相交于图中的P点,下列判断正确的是(   )

A.若用a、b两单色光分别通过同一双缝干涉装置,a光的干涉条纹间距比b光的小

B.a光通过玻璃砖的时间大于b光通过玻璃砖的时间

C.从某种介质以相同的入射角射入空气时若a光能发生全反射,b光也一定能发生全反射

D.如图乙,把a单色细光束垂直于三棱镜AB面入射,两块同样的玻璃直角三棱镜ABC,两者的AC面是平行放置的,在它们之间是均匀的未知透明介质,则出射光线可能是7、8、9(彼此平行)中的一条

题型:填空题

焊接过程中,每焊完一道焊缝后,焊工都应对焊缝进行以下哪些步骤()

A.对焊缝进行清渣或用钢丝清理

B.检查焊缝外观

C.表面有气孔,裂纹的要磨去

D.打磨应仔细进行,避免过热

题型:填空题

钳型电流表测量电流,可以在()电路电压上使用。

A.380/220V

B.35kV

C.6kV

D.10kV

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