关于俄罗斯港口和城市的叙述，正确的是（　　）

下列材料和用具中，制作人的口腔上皮细胞临时装片时应该用到的是（　　）

①生理盐水②清水③稀碘液④消毒牙签⑤切片．

    Keeping a diary in English is one of the best ways to improve our English writing ability.

    Compared with other forms of writing, it is shorter and takes ____(little) time. It can help us to develop the habit of thinking in English.____we stick to this practice,____ (gradual) we'll learn how to express (表达) ourselves in English. In keeping a diary in English, we certainly run up against many ____ (difficult). In the first place, it often ____(happen) that we have trouble ____(find) proper words and phrases to give expression to our mind. And____ is very hard for us to put them into English properly.

    As far as I am____(concern), my suggestion is that we should always have a notebook and a Chinese­English dictionary within easy reach. We can also turn to our English teacher for help, if necessary. In short, I believe that it is ____great use to keep a diary in English for the development of ____ (we) writing skills.

下列有关Fe₂（SO₄）₃溶液的叙述正确的是（　　）