题目

如图所示将一棵银边天竺葵（银边部分不含叶绿素）在黑暗中放置24小时后，选一健壮的叶片，用不透光的两块软木片在A处从正反两面遮住，然后将整个植株移到阳光下．数小时后，将选择的叶片摘下，去掉软木片，经酒精吸色处理后加数滴碘液．试回答：（1）银边天竺葵边缘不呈现绿色是因为不含______． （2）A处颜色______，原因是__          ____，从而说明了___        ___． （3）B处颜色______，原因是_                    _____． （4Pop music is the name for different forms of popular, commercial(商业) music. It had its beginning in the USA and spread throughout the whole world during the 1950s and 1960s. It is widely liked by the young people. The best known early form of pop music was “rock’ n’ roll”; another was “blues”. A more recent development is “folk-rock”. Pop music has taken the place of native music in many parts of the world; it has caused the number of people for jazz to become much smaller than it was in the 1950s and earlier, and it has now begun to rule musical stage productions. It’s a big industry. Much pop music is without artistic value, but the work of some pop singers, e.g. the Beatles, Bob Dylan, the groups like Floyd and Crosby, Stills and Nash, is on a higher musical level. And there is still a great interest in it today. Pop music concerts and festivals are held all over the world. All of the following forms belong to pop music EXCEPT __________________. A. blues                    B. rock’ n ’roll           C. jazz               D. folk-rock According to the article, the number of people for jazz in the 1950s and earlier was ___________ it is today.    A. much greater than   B. much smaller than    C. as great as     D. as small as Which of the following is TRUE?    A. No pop music is on a high musical level.    B. Much pop music is very artistic.    C. Pop music is highly artistic.    D. Not all pop music is without artistic value. “It is a big industry” means that _______________.    A. it makes a lot of musical instruments (乐器) B. it is a big musical and commercial business C. the pop singers are very hard-working D. pop music is on a very high musical level