题干

某实验小组欲从被石油污染过的土壤中筛选出能分解石油的细菌,下列操作中错误的是

A:利用平板划线法可对细菌进行计数

B:以石油为唯一碳源的培养基可用于筛选

C:目的菌不能利用无机碳源合成有机物

D:稀释土壤时需在火焰旁的目的是防杂菌污染

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A

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    Why do many people play sports? You might say “to get exercise'' and you'd be right. To have fun? That's true, too. But there's more.____According to the Women's Sports Foundation, girls who play sports get a lot more than just fit.

    Girls who play sports do better in school. ____But research shows that girls who play sports do better in school than those who don't. Exercise improves learning, memory, and concentration, which can give active girls an advantage in the classroom.

    Girls who play sports learn teamwork and goal-setting skills. Sports teaches valuable life skills. When you working with coaches, trainers, and teammates to win games and achieve goals, you're learning how to be successful. ____

    Sports are good for a girl's health. In addition to being fit and maintaining a healthy weight, girls who play sports are also less likely to smoke. And later in life, girls who exercise are less likely to get breast cancer.

    ____ Girls who play sports feel better about themselves. Why? It builds confidence when you know you can practice, improve, and achieve your goals. Sports are also a feel-good activity because they help girls get in shape, maintain a healthy weight, and make new friends.

    Exercise cuts the pressure. Playing sports can lessen stress and help you feel a little happier. How? ____ Friends are another mood-lifter. And being on a team creates tight bonds between friends. It's good to know your teammates will support you—both on and off the field!

A. Please take action to play games.

B. Playing sports boosts self-confidence.

C. Playing sports is good for your grades.

D. In fact, there are at least 5 more reasons.

E. Those skills will serve you well at work and in family life.

F. You might think that athletics will take up all your study time.

G. The brain chemicals released during exercise improve a person's mood.