怎样用直接法配制标准溶液?
参考答案:
准确称取一定量的基准物质,溶解后定量地移入量瓶中,用溶剂稀释到标线。根据称取的基准物质的重量和量瓶的容量直接计算溶液的准确浓度。
根据单词提示完成句子。
1. It is ____________ (a) egg.
2. Are ____________ (that) eggplants?
3. How many ____________ (flower) are there?
4. I want ____________ (climb) the tree.
5. ____________ (can) she draw?
No, she ____________ (cannot).
涵洞的病害有哪些?