pp2-119

david_he

Ahthough copper was hammered into toos and ornaments by some early inhibitants of North America,the smelting and casting of copper were unkown between them.

Answerd) between->among.

My question:it is (the smelting and casting of copper),not (the smeting and the casting of copper),so (were ->was).

我记得：the smelting and casting of copper应该按单数处理吧？

hoiabm

smelting and casting 是2个名词，所以后面用were~

而them是指：early inhibitants 所以不能用between,改称among

david_he

thanks