Owing to global warming, sea levels are rising and rain forests are dying. It’s clear that humans     1    (cause)most of the warming over the past century by releasing greenhouse gases, the levels of which are     2    (high)now than at any time in the past.

Global warming is causing a set of changes to the earth’s climate     3     vary from place to place. Many people think that global warming is the same as climate change. However, scientists use “climate change” when describing the complex shifts now affecting     4    (we)planet’s weather and climate systems—in part because some areas     5    （actual）get cooler in the short term.

Climate change includes not only rising average temperatures but also extreme weather events and a range of other     6    (consequence). All of them are appearing as humans continue to add greenhouse gases to the atmosphere,     7    (change)the rhythms(节奏)of climate that all living things have come to rely     8    .

What shall we do and what can we do     9    (slow) this human-caused warming? How shall we deal with the changes we’ve already set into motion? While we struggle to figure it all out,     10     future of the earth hangs in the balance.

Poor environment is connected with poor health. Now a new public-health     1     (tend)is becoming apparent: Making indoor air cleaner.

Let’s take schools for example. Across Denmark, France, and Sweden, researchers found that indoor-air quality in 66% of classrooms fell short     2     healthy standards. Outdoor-air pollution can get inside buildings — childhood     3     (expose)can affect their physical development and academic performance, and cause cancer.

The problem extends well beyond classrooms. Many people spend more than 90% of their time     4     (stay)indoors. Spaces in buildings with poor air may cause a range of diseases — headaches, shortness of breath, coughs and discomfort of eye, nose, throat and skin. Poor air     5     (blame)for decreased productivity in the past few years.

Covid-19 has brought a new urgency to the matter     6     (great). More investment would be well spent. Better indoor air improves academic development — math     7     reading scores go up. Meanwhile pupils are     8     (attentive)in class. Poor air indoors is the     9     (forget)part when people improved public health. Covid-19 should lead policymakers to focus on the problem,     10     is of great importance for people’s well-being.