Teachers need to be aware of the emotional, intellectual, and physical changes that young adults experience. And they also need to give serious 　1　to how they can best 　2　such changes. Growing bodies need movement and 　3　, but not just in ways that emphasize competition.　4　they are adjusting to their new bodies and a whole host of new intellectual and emotional challenges, teenagers are especially self-conscious and need the 　5　that comes from achieving success and knowing that their accomplishments are 　6　by others. However, the typical teenage lifestyle is already filled with so much competition that it would be 　7　to plan activities in which there are more winners than losers,　8　, publishing newsletters with many student-written book reviews, 　9　student artwork, and sponsoring book discussion clubs. A variety of small clubs can provide 　10　opportunities for leadership, as well as for practice in successful 　11　dynamics. Making friends is extremely important to teenagers, and many shy students need the 　12　of some kind of organization with a supportive adult 　13　visible in the background.
　　In these activities, it is important to remember that the young teens have 　14　attention spans. A variety of activities should be organized 　15　participants can remain active as long as they want and then go on to 　16　else without feeling guilty and without letting the other participants 　17　. This does not mean that adults must accept irresponsibility.  　18　, they can help students acquire a sense of commitment by 　19　for roles that are within their 　20　and their attention spans and by having clearly stated rules.
______

A.if only

B.now that

C.so that

D.even if