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【多选题】
下列无机盐离子中,对人体具有潜在毒性的是( )。A.
铅
B.
汞
C.
钙
D.
铁
E.
硒
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【单选题】what do many observers predict in view of the experience of the 20th century?
A.
Economic growth will slow down.
B.
Government budgets will increase.
C.
More people will try to pursue higher education
D.
There will be more competition in the job market.
【单选题】Which of the following statements about global carbon emissions are correct?
A.
In 2013, the largest national contributions to the net growth in total global carbon emissions in 2013 were China (58% of the growth), US (20% of the growth), India (17% of the growth), and EU28 (a decrease by 11% of the growth).
B.
From 1870 to 2014, cumulative carbon emissions totaled about 545 Gt
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