()的婴儿能集中注意10----12分钟。
A、1岁半
B、1---3个月
C、2岁
D、半岁
参考答案:C
从C、H、O、N、Na、Ca等6种元素中选择恰当的元素,用离子符号、化学式按下列要求填空:
(1)铵根离子______;
(2)可改良酸性土壤的碱是______.
用所给单词的正确形式填空,每空一词。
1. My grandfather wants to live in a _____ (peace) countryside.
2. Male _____ (wolf) will protect their families if there is danger.
3. The little pet's _____ (die) makes me very sad.
4. We should take the _____ (follow) actions to help the wild animals.
5. _____ (sad), we lost the match in the end