U. S. senators serve for______years after they are elected.A．fourB．sixC．threeD．two

U.S. presidents normally serve a（n) ______ term.A．two－yearB．four－yearC．six－yearD．eight－yea

There are______dressmakers in the U. S. than in European countries.A．far fewerB．so fewerC．

It can be inferred that in the U. S. ______.A．business lunches last longerB．lunch usually

000 unemployed people signed up for financial assistance in the U. S. in early______.A

Pakistani and U. S. officials have formally signed an agreement before they______.A．fought

______lie（s)between the boundary of Canada and the U. S. and serve（s)as the boundary betwe