基础专项：时间轴与状态变化

唯一新困难：时间变化

文章会对比过去、转折期和现在。干扰项常把过去事实当成现状，把试验期趋势写成长期结论，或忽略 initially / later / now / no longer。本课只训练时间轴。

自拟短文

When electric bicycles first appeared in the delivery market, their limited range restricted them to short routes. Battery capacity later improved, and by 2022 several firms were using them for full-day urban schedules. They have not replaced vans on long rural routes, but their role is no longer confined to brief trips.

题目：What has changed about electric bicycles?

A. They are now used only for short journeys.
B. They have replaced vans everywhere.
C. Improved batteries have expanded their urban use.
D. Their range became worse after 2022.

画三点时间轴

最初：续航限制短途。后来：电池改善。到2022：可承担全天城市安排。当前限制：仍未替代农村长途货车。C 保留变化和场景。

A 把过去状态当现在，并与 no longer confined 冲突；B 删除 rural 限制并扩大为 everywhere；D 反向解释 improved。

时态不是装饰

first appeared 定位历史起点，later improved 表变化，by 2022 were using 表到某时已出现的实践，have not replaced 连接过去到现在的未完成状态。选项必须落在相同时间层。

迁移练习

能否推出电动自行车已经适合所有配送任务？

**答案：**不能。原文明确保留长途农村路线限制，只说明城市用途扩大。

独立动作验收

画出“过去—变化—现在能力—当前限制”四格时间轴，并逐项标出 A、B、D 错在时间还是范围。