与双抗体夹心法相比，ELISA间接法的主要优点是（）

A.有较大的放大作用

B.减少了操作步骤

C.减少了冲洗次数

D.可以用一种酶标抗体检测各种与抗原相应的抗体

E.缩短反应时间

A certain truck manufacturer must have sales of $4.5 billion to break even this year. If the manufacturer had sales of $ 1.9 billion for the first half of the year, then, to break even for the year, its sales for the second half must be approximately what percent higher than its sales for the first half ？（）

A．11%

B．16%

C．27%

D．37%

E．58%