What ______ public is concerned about is whether medical workers and scientists will be able to find _____ cure for this new disease in a short time .

A．不填；a

B．不填；the

C．the ; 不填

D．the ; a

783.5+52.96-35.18-15.5+58.35的值是：

A．845.15

B．846.24

C．844.13

D．845.66