______找平层能增强防水层与基础的粘结，避免防水层膨胀，尤其适用于防水层冬季施工。

A．水泥砂浆

B．混凝土

C．混合砂浆

D．沥青砂浆

Why does a lack of sleep cause people to gain weight().

A.Because people burn fewer calories when they are awake.

B.Because people feel hungry when they lack sleep.

C.Because their hormones stay unchanged.

D.Because people don’t exercise when they don’t have enough sleep.