层门只能在井道内人为解脱门锁后才能打开，在层门外只能用（）才能打开
参考答案：专用钥匙
Krashen identifies three kinds of affective variables related to second language acquisition: （）.
A. motivation, self-confidence and anxiety
B. comprehension, acquisition and anxiety
C. input, competence and self-confidence
D. situation, motivation and self-confidence
预防流行性出血热的关键性措施是
A．防鼠、灭鼠B．防螨、灭螨C．个人防护D．接触鼠类后可试用胎盘球蛋白注射E．防止皮肤破损
