1. An observant visitor would soon notice that it is filled with what looks like a thick, greyish substance.
    但细心的客人很快就会发现瓶里装的是一种看上去黏稠，颜色发灰的东西。

2. An observant visitor would soon notice that it is filled with what kooks like a thick, greyish substance.
    明眼的来访者很快就注意到瓶里装的是一种看上去浓厚的淡灰色的物质。

3. You are very observant, Cathy.
    卡西, 你目光好敏锐。