在优质碳素结构钢生产中为什么要求Mn/Si＞2.5？

下面五个家庭或个人正在考虑各自的活动安排。请阅读第1—5题中他们的实际情况，从A—F的六张图片中选取符合要求的最佳选项。其中有一项是多余选项。
Mrs Anderson is a housewife with three children. She is a good mother and cares for her family. On school nights, she usually reads books to the children while on weekends she’d like them to be close to the nature, enjoying the lovely living creatures.
Mr Scott is a well-known professor who teaches South-East Asian history in UBC. He is also an excellent photographer. In his spare time, he always goes outdoor to get some inspiration.
Mr Smiley is an electronic engineer who is busy all week except Saturday. He has two sons and they are crazy about doing tricks with each other. However, they are full of imagination and they hope that they will be as famous as David Copperfield.
Mrs Reid is a doctor. Basicallly, she works all week except Sunday. She is also a good mother whose son is only seven. She believes science and history are of great importance. As long as she is free, she will company her son to all kinds of activities or exhibitions.
The Morgans are an old couple who have been retired for over five years. Mr Morgan is fond of fishing while Mrs Morgan likes gardening. But their cats are naughty. They either eat their fish or play with the plants in the garden. So they want to train them to follow rules.

A Pet Training Class Rather than use electronic devices, train you pet the traditional way! Basic skills class Fun tricks class Advanced skills class in Pet training please add “Every Saturday”above price info: Every Saturday $40 for 3 weeks	B AFRICAN SAFARI PARK A Drive-through Zoo Drive in your own car or take the special train. See lions, giraffes, zebras, and elephants without cages.	C HARRY POTTER MAGIC SHOW See magic tricks ●The quiet bell ●The intelligent ball ●The terrible message Two full hours Saturday morning Starts at 9:30 The Grand Cinema 741 High Street
D THE TAJ 100 years of pictures THEN AND NOW See the Taj in history from 1914 to 2014 Photography Exhibit April 20-April 30 City Art Museum 750 High Street Tuesday to Sunday 10 a.m to 5 p.m	E BELL TOWER TOURS Great view from the top! Climb 439 steps or take the elevator Learn the 300-year history Sundays only 8 am. To 3 pm No children under 8	F CHILDRENS MUSEUM Special Show on Inventors in History Make a Mobius Band Figure out a puzzle February 15—March 15 For children 5 and over and their parents Open every day except Wednesday 8--4