爬行类适应陆生的最主要的特征是皮肤(),缺乏(),()层增厚,产大型(),()
参考答案:干燥;腺体;表皮;羊膜卵;体内受精
全国银行间市场债券质押式回购实行标准券制度。( )
Thanks is a common _____ used in English. You can never use it too much.
A.word
B.words
C.expression
D.expressing