就销售商品而言,人类经历了货郎挑卖—门市销售—网络销售的变化过程。这一变化主要体现了
She hardly ever speaks French after class, for she is afraid ______ mistakes______ grammar.
.If you meet some new words, you can _____ in a dictionary.
---How do you study ____the final test? ---I study ____ working with a group.
--I’m worried about my math exam. ---______.I believe you can pass it.
A group of middle school students spent two weeks ____the jungle.