评价儿童体格生长，不规定"正常标准"而是用参照值范围，这是因为（） A.各系统发育不

平均每英亩土地仅能生产400磅amaranth，却能产出2400磅的小麦，或者说是 amaranth产量的6倍。于是，只要当amaranth的价格预计比小麦的价格高出6倍以上时，希望利润最大化的农民就会种植amaranth而非小麦。
以上论述依据下面哪个假设

A．比起一英亩小麦来讲，种植一英亩的amaranth并把它拿到市场上去销售所花费的成本并不高。

B．小麦是所有粮食中每亩产量最高的。

C．通过选择耕种哪种粮食，农场主对这些粮食的价格施加了显著的影响。

D．谷物的价格变化很快，农民不能改变种植不同谷物的面积来适应这种变化。

The Florida Sea Base Programs

Diving Adventure

If you are a diver, this is your program. During the program you will be making as many as nine dives (weather permitting), including a night dive. We have open dates in June, July and August for the summer months and for fall we have opening in September, October, November and December. Check out the dates today. Click here!

Sea Exploring!

The name brings back the memory of pirates(海盗) sailing the high seas of the past. This adventure is for larger teams of 18 to 20 teammates. Sailing on a tall ship with your team, you will be making memories that you will share for the rest of your life with anyone who will listen. Be sure and check out the dates we have open. Click here! We can fit your timetable to meet your needs with these great dates.

Live Aboard Diving

The Florida Sea Base has the sailing and diving programs joined for one wonderful adventure! On this adventure, you will spend your days not only in diving, but also in sailing around the Florida Keys. There are openings this fall and winter. Check now for open dates to spend your winter holidays in the keys. Click here! Fall dates are open now. Check them out today!

Just around the corner: the Christmas season in the keys! We have an opening for the Live Aboard program on December 26. Book today---it won’t last long!

Diving Certification(证书)

The Diving Certification program is designed for teammates who want to get a certification--- all who complete the week successfully will be offered PADI certification! Come and learn how to dive in the beautiful waters of the Florida Keys.

We have the following dates open: August 5, August 12, August 19, August 22 and August 26. We also have programs we offer in the fall: September 30, October 7, October 14, October 21, and many more dates. Check out the rest of the dates. Click here!

55. The text is most probably found _________.

A. in a newspaper            B. on the Internet

C. in a science magazine       D. in a book about Florida Sea

56. Colin wants to join in the Diving Adventure. He is supposed to have ______.

A. 9 dives                 B. 10 dives       

C. 19 dives                D. as many dives as he likes

57. According to this text, Live-Aboard Diving is special in that ____.

A. diving goes on during the sailing   

B. it is an adventure at sea

C. there are diving programs in it     

D. it is held in the Christmas season

58. The purpose of the text is mainly to ________.

A. teach        B. introduce       C. report       D. advertise

躁狂发作时的活动过多表现有（）

A.爱管闲事，整天忙忙碌碌

B.效率较正常时显著提高

C.对自己的行为缺乏正确判断，常常随心所欲，不考虑后果

D.注重打扮装饰，但并不得体，招引周围人的注意

E.社交活动多，随便请客，行为轻浮

互感器校验仪的检定周期一般不超个（）

A.3

B.2

C.1

D.半年

起下钻气