SAT Crossing and recrossing the stream,stepping on or over slippery rocks,and following a trail that grew steeper and steeper,the hikers soon realized (how challenging )their day would be.这句话没错但为什么how challenging 那里是对的啊 不是应该是how to challenge吗?表目的 In 1850 Jim Beckwourth,a Black American explorer,discovered in the mountains of the Sierra Nevada a pass (soon becoming) an important gateway to California gold-rush country. 括号里为什么错了?
