题干

某实验小组探究”烟草浸出液对水蚤心率的影响“进行了以下实验:

[材料和条件]

15℃的室温条件下,用10只大小一致、水蚤心跳正常的成年水蚤,分为A、B两组进行实验,观察水蚤10秒内心跳次数;四份等量的香烟烟丝中分别加入20mL、30mL、40mL、50mL的蒸馏水浸泡1天的浸出液.(用于浸泡的蒸馏水越少,所得烟草浸出液浓度越高)

[实验方法]

①A组:每只水蚤先放在清水中计心跳次数,重复3次;

②B组:将A组的水蚤分别移入20mL、30mL、40mL、50mL蒸馏水的烟丝浸出液,计心跳次数,并重复3次;

③处理数据:分别计算出A、B两组实验数据的平均值,将得到的数据绘成如图曲线图.

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七选五

    Nail-biting(咬指甲) is one of the most common annoying habits in children. ____ But you needn't worry too much and as soon as you realize what's causing nail-biting, you can help your child overcome and stop it. So, here's what you can do about it.

    ____In some cases, children won't even realize they are biting their nails, let alone know why they are doing it. So make sure you have a conversation with your child (if he/she is old enough) and make him/her realize he/she is doing it and try to figure out why it's happening.____ It's important to agree on the level of your involvement. If he/she wants help, create a secret reminder that will make him/her stop without embarrassing him/her.

    Give alternatives (替代物).____ Depending on the age of the child, there are several things that you can offer such as a small ball, Play-Doh games, or any kind of other small toys.

    Use bitter solutions(溶液). Forcing a child to keep this solution on his/her fingers may feel like a punishment.____ Everything else will only lead to embarrassment and discouragement. Furthermore, some of these solutions contain pepper which burns if it enters a child's mouth or eyes. But if you have an adolescent child who wants to quit biting his/her nails, you may suggest and try out this solution.

A.It's also likely to continue as the child grows up.

B.Help the child become aware of the habit.

C.You should also consider asking for professional help.

D.Make an agreement on how you're going to stop it together.

E.The best thing children can do is communicate with their parents.

F.The child needs to go through the process painlessly and in agreement with you.

G.That will keep his/her hands occupied when he/she is likely to bite his/her nails.