Trắc nghiệm: must be treated.(A) Some underground water is (B) enough safe to drink. (C) but all the surface water (D) must be treated. | Gửi trắc nghiệm |
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Trắc nghiệm: must be treated.(A) Some underground water is (B) enough safe to drink. (C) but all the surface water (D) must be treated. | Gửi trắc nghiệm |