. He arrived at last, ________ .

A．tired and hungrily

B．tiredly and hungrily

C．tired and hungry

D．tired and hunger

以下正确的说法是

A．不同发育阶段生殖细胞的放射敏感性是相同的

B．精母细胞对放射不敏感

C．精原细胞对放射最敏感

D．精子细胞对放射很敏感

E．精子对放射非常敏感