发射机MT1501A/501A开机前单工/双工开关SIMPLEXDOUPLEX置于（

(B)

Tim Richter and his wife, Linda, had taught for over 30 years near Buffalo, New York—he in computers, she in special education. "Teaching means everything to us", Tim would say. In April 1998, he learned he would need a heart operation. It was the kind of news that leads to some serious thinking about life’s purpose.
Not long after the surgery, Tim saw a brochure describing Imagination Library, a program started by Doily Patron’s foundation (基金会) that mailed a book every month to children from birth to age five in the singer’s home town of Sevier, Tennessee. "I thought, maybe Linda and I could do something like this when we retire," Tim recalls. He placed the brochure on his desk, "as a reminder."
Five years later, now retired and with that brochure still on the desk, Tim clicked on imagination library. The program had been opened up to partners who could take advantage of book and postage discounts.
The quality of the books was of great concern to the Richters. Rather than sign up online, they went to Dollywood for a look-see. "We didn’t want to give the children rubbish," says Linda. The books-reviewed each year by teachers, literacy specialists and Dollywood board members-included classics such as Ezra Jack. Keats’s The Snowy Day and newer books like Anna Dewdney’s Llama series.
Satisfied, the couple set up the Richter Family Foundation and got to work. Since 2004, they have shipped more than 12,200 books to preschoolers in their area. Megan Williams, a mother of four, is more than appreciative "This program introduces us to books I’ve never heard of."
The Richters spend about $400 a month sending hooks to 200 children. "Some people sit there and wait to die," says Tim. "Others get as busy as they can in the time they have left.\

Why did the Richters go to Dollywood

A. To avoid signing up online.
B. To meet Dollywood board members.
C. To make sure the books were the newest.
D. To see if the books were of good quality.

按定额的编制程序和用途不同，可以把工程建设定额划分为（）。

A.施工定额

B.劳动消耗定额和机械消耗定额

C.预算定额、概算定额

D.机械消耗定额

E.概算指标和投资估算指标

UMG8900系统中，可以与MRPU板对插的单板有（）。

A、E1G系列单板

B、ME8T

C、MBGE

D、MBFE

E、P4L系列单板

F、MBAP

试述HPLC法与GC法用于检查药物中杂质时的五种方法及适用范围。

干管定线时其延伸方向应和二级泵站输水到水池、水塔、大用户的水流方向一致，以最近的距离，将一条或几条干管平行地布置在用水量较大的街区。平行的干管间距约为（）m。

a、100～300

b、300～500

c、500～800

d、800～1000