关于日本国土的描述，正确的是（    ）

已知sinα=$\frac{4}{5}$，并且α是第二象限的角，那么tanα的值等于（　　）

He____(放松)at home last weekend．

    It's going to be Sport Day on Friday. There are some students on the playground.

    They are doing sports. Amy is running. She can run fast. Sam is jumping. He can jump really high. Daming is playing football. He can play it very well. What is Lingling doing? She is playing basketball. She can catch the ball. But she can't catch it very well.

用已知浓度的盐酸滴定未知浓度的NaOH溶液（NaOH溶液放于锥形瓶中），选酚酞作指示剂，下列操作会导致测定结果偏低的是（　　）