学习化学的一个重要途径是科学探究，实验是科学探究的重要手段，下列化学实验操作不正确的是

根据短文理解从A、B、C、D四个选项中选择最佳答案填空。

    Once a rich woman invited Martin Brown, a famous singer to sing for her friends. But she 1 him to have dinner with them. She told him to eat 2 the servants(仆人).

    After the meal Martin stood up and said to the servants, “Now, my good friends, I 3 for you.” He sang several songs and the servants 4 quite pleased.

    Then the rich woman asked 5 to come to the sitting-room. “We are waiting for your songs. 6 you ready?” the woman asked.

   “I am 7,” Martin said. “I have sung already(已经). I usually sing 8 in one evening, and I can't sing 9.”

    And with a polite(礼貌) “10”, he left the rich woman's house.

下图示意“北半球某区域2013年1月4日14时和5日8时海平面气压（单位：百帕）分布”，读图完成下列问题。

在下图中用涂色部分表示 $\frac{3}{4}$ 。