语法与词汇 The asphalt at La Brea seeps to the surface, especially in the summer, and forms shallow puddles that would often have been concealed by leaves and dust.

A、 highlighted
B、 covered
C、 transformed
D、 contaminated

【正确答案】 B

【答案解析】句意：位于拉布雷亚的沥青特别容易在夏天渗出表面，形成浅浅的水坑，经常让落叶和尘土掩埋住。conceal此处意为“隐藏，遮住”，与cover同义。highlight突出，强调。transform改变。contaminate污染。因此，本题正确答案为B。