Which of the following is NOT mentioned in this passage?
A.Some runners looked like Elvis Presley.
B.Some runners were ready to put out a fire.
C.Some runners were participating in a wedding.
D.Some runners were serious about winning.
The largest footrace in the world is the 12 - kilometer Bay to Breakers race that is held in San Francisco every spring. This race begins on the east side of the city near San Francisco Bay and ends on the west side at the Pacific ocean. In 1993 there were 80, 000 people running in this race through the streets and hills of San Francisco. In the front are the serious runners who compete to win, and who might finish in as little as 34 minutes. Behind them are the thousands who take several hours to finish. In the back of the race are those who wear costumes just for fun. In 1993 there was a group of men all of whom dressed up like Elvis Presley. There was a group of firefighters who were all tied in a long line and were carrying a firehouse. One year there was a bridal (新婚的) party in which the bride dressed in a long white gown and the groom wore a tuxedo (晚礼服). They threw flowers to bystanders, and were actually married at some point along the route.
The main purpose of this passage is to ______.
A.encourage people to run
B.describe a popular activity
C.make fun of runners in costume
D.give reasons for the popularity of footraces
为促进铸铁石墨化,可采用下述方法()。
A. 提高W(C) 、W(Si),提高冷却速度 .
B.增加W(C) 、W(Si),降低冷却速度
C.降低W(C) 、W(Si),提高冷却速度
D.降低W(C) 、W(Si),降低冷却速度
A.2~5(W/O型);6~10(O/W型)
B.4~9(W/O型);8~10(O/W型)
C.3~8(W/O型);8~16(O/W型)
D.3~8(W/O型);6~10(O/W型)
E.2~5(W/O型);8~16(O/W型)
A.8-10μW/(cm2 ·nm)
B.15-20μW/(cm2 ·nm)
C.25-30μW/(cm2 ·nm)
D.35-40μW/(cm2 ·nm)
A.10000μW、s/cm2
B.100000μW、s/cm2
C.20000μW、s/cm2
D.300000μW、s/cm
A.Qw%=W包/W游
B.Qw%=W游/W包*100%
C.Qw%=W包/W总*100%
D.Qw%(W总-W包)/W游*100%
E.Qw%=(W总-W包)/W包*100%