为了胚胎的正常生长和发育，孵化时要求的相对湿度：前期（），中后期（），出雏期（）。
参考答案：60-65%；50-55%；65-70%
教学方法
根据下列各句句意及所给单词的汉语提示, 写出各单词的正确形式。
小题1:We were near the ________(边界)between France and Germany.
小题2:I will send one thousand lucky stars to you and let the good luck ________（围绕）you
小题3:There are many _______ (理论) about the origin of life.
小题4:It is generally accepted that smoking is _______ (有害的) to our health.
小题5:Do you want your vegetables cooked or________（生的）?
