钢筋混凝土中的钢筋是为了弥补混凝土（）的缺陷，这样制成的构件既能受压，又能受拉，从而扩大了混凝土的适用范围。
参考答案：抗拉能力低
根据句意及首字母提示完成单词。
1. A s______ is used for sending letters.
2. My hobby is c______ shells.
3. They didn't finish their composition because they r______ out of the time.
4. He's been collecting kites s______ he was six.
5. Tom has been collecting stamps since he was in Grade 1. He is a great c______.
戴入局部义齿后与基牙疼痛无关的因素是
A．基托伸展过长B．基托与基牙接触过紧C．支托上有高点D．卡环过紧E．设计不当基牙受力过大
