已知F₁，F₂为双曲线C：$x^2-y^2=1$的左右焦点，点P在C上，$\angle F_{1}P{F}_2={60}^{°}$ ，则$\left|P{F}_1\right|·\left|P{F}_2\right|=$  （ ）

阅读下面的文字，根据要求作文。
      成长路上的你，朝气蓬勃，看着流光溢彩的世界，宣扬着壮丽的词藻，不顾一切，奔向前方。一心向前的你是否注意到，在你的背后总有一双眼睛默默关注着你，为你欣喜骄傲，为你忧虑焦思，伴你荣辱与共。
      请以“背后的眼睛”为题，写一篇记叙文。
要求：①写自己生活中的事，有真情实感；
②文中不得出现校名、人名，如需出现，一律用“XXX”代替；
③不少于600字。

    A rainforest is an area ____ (cover) by tall trees with the total high rainfall spreading quite equally through the year. Rainforests have a great effect on the world environment because they can take in heat from the sun and adjust the climate.____the forest cover, these areas would reflect more heat into the atmosphere,____ (warm) the rest of the world. Losing the rainforests may also influence wind and rainfall patterns, potentially causing certain natural disasters all over the world.

    In the past hundred years, humans ____ (begin) destroying rainforests in search of three major resources: land for crops, wood for paper and other products, land for raising farm ____ (animal). This action affects the environment as a whole. For example, a lot of carbon dioxide in the air comes from burning the rainforests. People____ (obvious) have a need for the resources we gain from cutting trees____ we will suffer much more than we will benefit.

    Rainforests are often called the world's drug store. More than 25% of the medicines we use today come from plants in rainforests. However, fewer than 1% of rainforest plants have been examined for their____ (medicine) value. It is extremely likely ____ our best chance to cure diseases____ (lie) somewhere in the world's shrinking rainforests.