_____ no need to worry about the problem．The government has promised to have clean water _____ to us from door to door．

A．It is ; delivered

B．It is ; delivering

C．There’s ; to deliver

D．There’s ; delivered

流行性乙型脑炎是由乙脑病毒引起的急性中枢神经系统传染病，一般流行于（）.

A.春夏季

B.夏秋季

C.秋冬季

D.冬春季