GPS测量中，减弱电离层影响的措施包括（）、（）和利用同步观测求差。
参考答案：利用双频观测；利用电离层改正模型
(一)
[背景资料]
对地下防水混凝土工程施工质量应重点检查哪些方面是否符合设计和规范要求
用括号内所给词的适当形式填空。
小题1:My birthday is on the ________ (five) of June.
小题2:Look! There are some books on these ________(shelf).
小题3:There is ________(little) money in this pocket than in the one.
小题4:The book doesn’t belong to ________(he), his book is on his desk.
小题5:At weekends, there are so many ___________(shop) in the supermarkets.
