— Food problem is becoming a big one in China!

—I think the food ________ before going to shops or supermarkets.

A．is checked

B．is checking

C．should be checked

D．should check

进行性脊髓性肌萎缩（）。

A.累及脊髓前角细胞

B.累及脊髓前根

C.累及脊髓后索

D.累及脊髓前索

E.累及脊髓后根