题目：
其他题
Write down the numbers of the topic sentences in the following passages.
①People who talk and sing to plants have no mental problems at all, according to an agricultural expert. ②“In fact, singing and talking to plants makes them grow better,” says Dr Braymar. ③The reason is quite simple. ④When we sing or talk to plants, we exhale(呼出) CO2 which plants need to survive (continue to live)and grow better. ⑤Plants absorb (take in) CO2 through their pores(小孔) during the sunlight hours and produce oxygen which people to survive. ⑥Singing and talking have good effect on plants, however, only during the daytime. ⑦Singing or talking at bedtime will not help plants to grow better or grow faster.
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