题目

完形填空。 On a Saturday morning，I went camping in Green Natural Park with some friends. We were happy because it was a sunny day. All the way there，we sang songs and made jokes.   1  ，in the afternoon，when we finished our picnic(野餐)at one o'clock，it was dark and windy. Soon，it started to rain. Unluckily，none of us brought a(n)  2  .We ran about but couldn't find any places to   3 . Twenty minutes passed and it was still raining. There was a long way to go  4  we reached the campsite(野营地).It was 5  worse because our compass(指南针)showed that we 20、阅读材料并回答问题：材料一：通常食醋中约含3%～5%的醋酸．醋酸的化学式为CH3COOH，在温度高于16.6℃时是一种无色液体，易溶于水，醋酸具有酸的通性．材料二钙是人体的一种常用元素，人们每日必须摄入一定量的钙．动物的骨头中含有磷酸钙，但磷酸钙难溶于水，却能跟酸反应生成可溶性的钙盐．（1）在10℃时，醋酸的状态是固态；（2）生活中能否用铝制品来盛放食醋？不能原因因为铝会与食醋中的醋酸反应；（3）人们在熬骨头汤时，常常会加入少量食醋，这样做的理由是使不溶于水的磷酸钙转变为可溶于水的钙盐．