下图中哪个苹果是正确的?
答:第二个与第四个苹果是正确的。
公比为2的等比数列{an} 的各项都是正数,且 a3a11=16,则a5=( )
This is my classmate. She's a girl. Her name is Jane. She's twelve years old. She's thin and tall. She has long and black hair. She has two big eyes and a small nose. She has a skirt. It's red. She has a pair of trousers, too. They are red. But her skirt is old. She wants to buy a new skirt. Look, what can she do? Oh, she can skip a rope. This is her rope. It's long. It's blue.
生物圈是地球上最大的生态系统,下列有关叙述正确的是( )
第一步:配制无菌葡萄糖培养液和活化酵母菌液
第二步:按如表步骤操作
装置编号
A
B
无菌马铃薯葡萄糖培养液/mL
10
活化酵母菌液/mL
0.1
温度(℃)
5
25
第三步:用血球计数板统计起始酵母菌数,并做好记录.
第四步:将各装置放在其他条件相同且适宜的条件下培养.
第五步:连续7天,每天同一时间取样计数,做好记录.
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