在职研究生英语（一）
阅读短文，选出填入空格最合适的一项： Much of the software …
第 4 题单选题模拟题较易
阅读短文，选出填入空格最合适的一项：
Much of the software that keeps the internet running is written by volunteers and shared at no cost. ___, the programs that let websites send data securely are often maintained by a handful of unpaid developers in their spare time.
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