1. (2019年北京卷)No matter what you like to do, there is a way to get involved in various ________ (activity) on Earth Day. You can plant a tree, make a meal with locally grown vegetables, or save power—the possibilities are endless.
解析：根据修饰语various可知，此处应用名词复数，指各种各样的活动。
答案：activities
2. (2019年浙江卷)Other American studies showed no ________(connect) between uniforms and school performance.
解析：no用来修饰名词，此处用单复数形式均可。
答案：connection/connections
