玻璃仪器洗涤干净的标志是______．
根据液体的表面张力以及玻璃的性质，玻璃是会被水浸润的．（放在洁净的玻璃板上的一滴水，会附着在玻璃板上形成薄层．把一块洁净的玻璃片进入水里再取出来，玻璃表面会沾上一层水．这种现象叫做浸润．）如果有水滴或股流而下，说明玻璃表面有让水不浸润的物质的存在，间接证明玻璃不干净．
故本题的答案是：洗涤过的玻璃仪器内壁附着的水既不聚成水滴，也不成股流下．
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Ted: Oh, I'm exhausted. I had a bad morning. Bob: What l_____? Ted: Well, first I 2_____. By the time I 3_____, my dad had already gotten in the shower. Bob: Oh, what a pain. Ted: So, after he 4_____ the shower, I took a quick shower and 5_____. But by the time I went outside, the bus had already left. Bob: Oh, no! Ted: So I ran all the way to school. But when I 6_____ school, I realized I 7_____ my backpack at home. Bob: No wonder you look stressed out. |