多囊卵巢综合征患者应预防下列哪种肿瘤的发生（）
A.卵巢癌
B.子宫颈癌
C.子宫内膜癌
D. * * 癌
E.外阴癌
参考答案：C
Read and translate. 翻译下列句子。
1. What did you do last weekend?
2. Did you help them clean their room?
3. I visited my grandparents.
4. Wu Yifan was busy last weekend.
5. Yesterday was a fun day.
建设性反馈具有哪些特点？
