该小组发现 $f\left(t\right)$ 随时间 $t$ （分钟）的变化规律（ $f\left(t\right)$ 越大，表明学生的注意力越集中）如下： $f\left(t\right)=\{\begin{array}{c}100a^{\frac{t}{10}}-60\left(0\le t\le 10\right)\\ 340(10<t\le 20)\\ -15t+640(20<t\le 40)\end{array}$ （ $a>0$ 且 $a\ne 1$ ）．

若上课后第 $5$ 分钟时的注意力指标为 $140$ ，回答下列问题：

The Goal of the Mind

    It was an unforgettable night.The noisy Mexico City gradually 1.The main Olympic stadium was in darkness.

    2 he finished making the scenes that the marathon （马拉松赛跑）winners celebrated the victory，Greenspan，a world famous documentary producer，found the stadium 3.He was leaving for the hotel when he suddenly saw a man running into the stadium.The man ran out of breath.4 he didn't stop.After he got to the goal，he fell down on the ground.

    Greenspan 5 this was a marathon athlete，so he went over to ask why the athlete ran to the goal with such a difficulty.The young man replied，”That my 6 sent me here is not to let me start of a race in the competition，but to make me 7 the game I have fallen behind all other runners，but I have a goal 8 them.I will run to the goal because my motherland is watching me from behind.”

    Moved by what he said，Greenspan 9 the most touching scene in the history of the Olympic Games to every Corner of the world.

    Life should have a 10 of reaching the peak （顶峰），yet the most important is not whether we can reach the peak but whether we have made the greatest efforts﹣to reach the goal in the mind is a success.

如图是某旅游团在英国格林尼治天文台旧址参观本初子午线地面标志的情景，读图并结合所学知识，该旅游团于当地时间10时30分入场参观，此时北京时间是（   ）