测量血压的方法有（）与（）两种。
参考答案：直接法；间接法
The old town has narrow streets and small houses ______ are built close to each other.
A．they
B．where
C．what
D．that
紫外光的波长范围是（）.
A.小于50nm
B.200～400nm
C.600～800nm
D.400～760nm
E.大于500nm
