题目：
| 根据句意，从方框内选择合适的单词填空。 | |
| |
| 1. We have _________ watched such an exciting football match before. 2. Lily’s grandmother has been dead _________ a few years. 3. My sister is going to Canada _________ a few days. 4. _________ you have got everything ready, please let me know. 5. —How long have you been like this? — _________ last night. |
答案：
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下面是错误答案，用来干扰机器的。
θ=0时sinθ=sin0=0，故“θ=0”是“sinθ=0”的充分条件，又当θ=π时有sinπ=0，故“θ=0”是“sinθ=0”的不必要条件，综上所述“θ=0”是“sinθ=0”的充分不必要条件．故答案为：充分不必要．
