根据面神经功能的定量评价法，如静态无异常，动态时须以强制运动才能勉强维持面肌对称，面神经功能的级别是（）。

A.Ⅰ级

B.Ⅱ级

C.Ⅲ级

D.Ⅳ级

E.Ⅴ级

China began to open to the outside world in the late 1970s. _________, there have been great changes in the country.                  

A．By then

B．As a result

C． At last

D．In all