Whales have been facing serious danger for a long time.

First, due     1     the greenhouse effect, glaciers are melting, and some living creatures in the Antarctic and the Arctic are in danger of     2     (extinct). Besides, with global warming becoming worse, life in other parts of the ocean has also been     3     (constant) affected, including whales.

Secondly, whaling activity is another killer. Historically, whaling has been popular in some overseas countries, such as England, Japan and Norway.     4     (regard) whales as a money-making machine is the reason why some people’s whaling can’t     5     (stop) easily. A kilogram of whale meat can fetch about $ 100 in Japan. Besides, advanced technology has increased the efficiency of whaling and gradually reduced the number of whales. What’s more, some countries are still on whaling in     6     name of science.

The fact     7     whales have become endangered animals is alarming us. Some     8    (organization) have realized the importance of saving them and have begun working hard to do something for them. The international community     9    (make) a strategy against commercial whaling. In my opinion, governments should also make laws     10    (protect) whales.

In late April 2017, a violent storm swept through the southern United States,     1    (destroy) more than $ 1 billion in property and killing 35 people. But it was     2    wonder that a group of birds sensed the oncoming disaster and left long before the first clouds arrived. A year earlier, a science team had tagged golden-winged warblers (莺) with leg trackers     3    ( study) their annual migrations to South America. Two days before the storms     4    (strike), five golden-winged warblers flied away, traveling south to the Florida coast.

It's the first time that the birds which normally migrate with the seasons     5    (observe) to fly away when a big storm hits. The researchers suspect this behavior occurs only when the threat of     6    (injure) outweighs the energy costs of a long trip. But nobody knows     7    the birds guessed the storm's harm and left so soon.     8    ( puzzle) by it, the scientists initially reasoned that changes in weather—atmospheric pressure, temperature or wind speed—signaled the upcoming disaster. Yet when they checked weather records, none of these factors waved     9    (significant) before the storm. Instead, the team thinks that the approaching storms created a disorder of infra sounds, low-frequency sound waves, that birds can hear,     10    humans can't.