---Wow! These inventions are amazing—They were all invented years ago.A. hundredB. hundre

问题补充：

---Wow! These inventions are amazing．

—They were all invented years ago.

A. hundred

B. hundreds

C. hundred of

D. hundreds of

答案：

A. hundred

B. hundreds

C. hundred of

(答案→)D. hundreds of

解析：英语中数词表示概数时，后面加s，和介词of搭配使用。用原形时表示具体数字和数词搭配使用。句意：喔，这些发明太神奇了。——他们是多年以前发明的。结合语境可知下文表示概数，故选D。