在1977年，中国进出口总额还不到150亿美元，仅占世界贸易总额的0.6%。

A.In 1977, the total sum of Chinese imports and exports was less than $15 billion, put Ch
B.In 1977, the sum total of Chinese imports and exports was less than $15 billion, puttin
C.In 1977, the sum total of Chinese imports and exports was less than $150 billion, putti
D.In 1977, the total sum of Chinese imports and exports was less than $150 billion, putti