Exercise 1: sample answer

Electric assist makes hills, headwinds and long distances much easier, so people who were not fit enough, or were older or had limited mobility, can cycle (check). It also makes heavy loads practical, so cargo bikes can carry children, shopping and deliveries, and it lets commuters arrive without being hot and tired, so the bicycle can replace more car trips. The trade-offs are cost, battery safety and recycling, theft, and higher speeds on shared paths (check).