There are fifty studentsin this class, ________ of them are boys, so the number of the boys is 30.
句意：班上有50名学生，五分之三是男生，因此男生的数量是30人。
考查分数的表达。分数是由基数词和序数词一起来表示的。基数词作分子，分子是three；序数词作分母，除了分子是1以外，其他情况下序数词都要用复数形式，此处分母用序数词的复数fifths。故选B。
There are fifty studentsin this class, ________ of them are boys, so the number of the boys is 30.
—________ of the city________ covered with parks and gardens.
—Wow, it’s really a green city.
—Susan, how many womenteachers are there in your school?
—Inour school, _______of the teachers _______ women teachers.
About ________ of thestudents in Kaili ________ to school boy bus.
—Dear, how is yourhomework going?
—Oh, mom, I've justfinished ________ of it.
Now, everybody, pleaseturn to Page ________ and look at the ________picture.
Five ________ new bookswere sold out last month.
—China is a greatcountry with a history of about five ______ years.
—Yes. And ______ of foreigners come tovisit it every year.
Sweet wormwood(青蒿)is a common plant inChina and Tu Youyou is the woman _________used the special power of the plantto save __________lives.
In our school everystudent has to choose a club to join, so about one ________ students havejoined the Sports Club.
