右图为存放水果时，空气中的氧气浓度(x)与水果释放的 CO2 相对量(y)之间的关系曲线。贮存水果应选择的最佳氧气浓度是（ ）
The sign means you shouldn't ______ photos here. A. take B. talk C. taking
Ben，open the window please. ______ close it. A. Don't B. Aren't C. Not
It's time ________ some cakes. A. to B. for C. for have
The boys ________books in the classroom now. A. are looking B. are reading C. are seeing
同学们，生活中你一定见到过不少的标志语吧！你能把下面这些标志送回家吗？
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