It just isn’t fair. _____ I was working as a waiter last month, my friends were lying on the beach.

A．Whenever

B．Though

C．For

D．While

对于男生长胡须和声调变低起直接作用的是        （    ）

A．雄性激素

B．雌性激素

C．促性腺激素

D．生长激素