Previous studies conducted in high-income countries have provided evidence about how lifestyle behaviours and high adiposity levels in early life, including adolescence, is asso- ciated with cardiometabolic and cardiovascular risk factors in middle and later life

这里的is对不对？

去新版论坛查看/参与投票

is是从句 how lifestyle behaviours and high adiposity levels in early life ..... 的谓语动词。本例的用法我觉得是对的。看这类句子，不能光从语法上着眼，而要从作者所要表达的意思着眼。记得一位语法专家（是薄冰吧）说，当牵涉到个体与整体的关系时be动词用单数形式还是复数形式有规则或则惯例可循。网上我找到一些例句：

例如，

单形集体名词被视为一个整体时，用单数动词。如：

The enemy is retreating. 敌人开始撤退了。

被视为若干个体时，则要求复数动词。如：

The enemy were encamped on the hill-side. 敌人在山坡上扎营。

并列主语与动词的一致有几种情况。

1)当“名词+and+名词”结构表示一种事物或一种概念时，应用单形动词。如：

(1)Fish and chips is a popular supper. 炸鱼土豆片是一种很受欢迎的晚餐。

(2)The poet and writer has come. 那位诗人兼作家来了。

(3)Peter, and perhaps John, plays football. 彼得，也许还有约翰，常踢足球。

本例中作者也许是把lfestyle behaviours and high adiposity levels看成一个整体。