【正确答案】 C

【答案解析】[解析] widen：变宽；加宽。broaden：变宽；扩大。Trails broadened into roads. 小径变成了宽阔的道路。extend：延伸；延长。The builders extended the road for three more miles. 筑路人把道路延长了三英里。stretch：舒展；延伸。The forests stretch for hundreds of miles. 森林绵延数百英里。traverse：穿过；横贯。The railway traverses hundreds of miles of desert. 这条铁路横贯沙漠数百英里。