Road running often offers those 19 a range of challenges such as dealing with hills, sharp bends, rough weather, and so on.
答案：(B) involved
those involved 是固定用法，意為「參與其中的人」，involved 是過去分詞當形容詞、帶被動語意；involving 為主動，to involve 是不定詞，are involved 會使句子出現兩個動詞。
答對率 26%。
involve 你大概只記得「牽涉」，而且多半見於 be involved in an accident（捲入事故），所以看到 those ___ 這個位置不知道要填什麼。those involved ＝「參與其中的人」，是英文很常用的簡潔說法，等於 those who are involved。
人是「被牽涉進去」的一方，所以用過去分詞 involved；involving 是主動，會變成「正在牽涉別人的那些人」，方向錯了。同一類的還有 the people concerned（相關人士）、the items mentioned（提到的項目）、the students selected（獲選的學子）——都是「名詞＋過去分詞」，把 who are 省掉。
those involved（參與其中的人）、the people concerned（相關人士）、be involved in（涉入、參與）、get involved（參與其中）、involvement（參與）。
Road running is one of the most popular and accessible athletic activities in the world. It refers to the sport of running on paved roads or established paths as opposed to track and field, or cross country running. The three most common 16 for road running events are 10K runs, half marathons (21.1K), and marathons (42.2K).
Road running is unique among athletic events because it 17 all ages and abilities. In many cases first time amateurs are welcome to participate in the same event as running club members and even current world-class 18 . Sometimes it may also include wheelchair entrants.
Road running often offers those 19 a range of challenges such as dealing with hills, sharp bends, rough weather, and so on. Runners are advised to train prior to participating in a race. Another important factor contributing to success is a suitable pair of running shoes.
Road running is often a community-wide event that highlights or raises money for an issue or project. 20 , Race for the Cure is held throughout the U.S. to raise breast cancer awareness. This race is also run in Germany, Italy, and Puerto Rico.