桌子上放有质地均匀，反面相同的4张卡片．正面分别标有数字1，2_爱下问搜题

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问题解答题

桌子上放有质地均匀，反面相同的4张卡片．正面分别标有数字1，2，3，4，将这些卡片反面朝上洗匀后放在桌面上，先从中任意抽出1张卡片，用卡片上所标的数字作为十位上的数字，将取出的卡片反面朝上放回洗匀；再从中任意抽取1张卡片，用卡片上所标的数字作为个位数字．试用列表或画树状图的方法分析，组成的两位数恰好能被3整除的概率是多少？

答案

列表：

个位数十位数	1	2	3	4
1	11	12	13	14
2	21	22	23	24
3	31	32	33	34
4	41	42	43	44

树状图：

（3分）

∴一共有16种情况，能被3整除的两位数的有5种情况，

∴能被3整除的两位数的概率是

5

16

．（6分）

完形填空

We sometimes call the lion “the king of the jungle (丛林)” because it is stronger and more dangerous than other animals. It can run faster than many animals and it can hunt (捕猎) the best. It is the highest animal in the   21 food chain (食物链).[
In the sea, the shark is one of the animals at the 22 of the food chain. It can swim faster than most other sea animals, and it can use its big teeth to eat them.
What is at the top of the world’s food chain? 23 are! We are not the biggest or fastest, but we are the   24 We could not run faster than cheetahs (猎豹), so we 25 cars and now we can move the fastest. We could not 26  better than lions, so we invented guns (枪). Now we can hunt the best.
People’s inventions are clever, but they can be dangerous, too. For example, people invented 27 , and now they make the air and rivers dirty. This can make   28 changes. Dirty rivers kill fish. Then bears cannot eat the fish and the bears die. If we kill one part of the food chain,   29  also die. Remember that we are a part of the food chain, so we are in danger too! If we protect animals, we are protecting   30 ! We should and we could do something for the world!

A．strongest	B．cleverest
C．most special	D．most important

B．another part

C．other parts

D．the other parts

单项选择题

常用于手术器械等耐热物品灭菌的方法是

A．间隙灭菌法
B．滤过除菌法
C．巴氏消毒法
D．流通蒸气消毒法
E．高压蒸气灭菌法