恩格斯认为,人与动物的根本区别在于(),并认为在人类的进化过程中,经过了三个依次递进的阶段,即()()和()的人。
参考答案:制造工具;“攀树猿群”;“正在形成中人”;“完全形成”
The parents were unsettled for the first few days, _____ about their son's safety. [ ]
A. having worried
B. to worry
C. being worried
D. worried
哪些人可以申请宣告婚姻无效?