11. mean to doing/to do

mean to do 打算、想
mean doing 意味着
I mean to go, but my father would not allow me to.
我想去，但是我父亲不肯让我去。
To raise wage means increasing purchasing power.
加工资意味着增加购买力。

12. begin( start) doing/to do

begin / start to do sth
begin / start doing sth
1) 谈及一项长期活动或开始一种习惯时，使用 doing.
How old were you when you first started playing the piano?
你几岁时开始弹钢琴？
2)begin, start 用进行时时，后面动词用不定式 to do
I was beginning to get angry.
我开始生起气来。
3) 在 attempt, intend, begin, start 后接 know, understand, realize 这类动词时，常用不定式 to do。I begin to understand the truth.
我开始明白真相。
4) 物作主语时
It began to melt.

13. 感官动词 + doing/to do

     感官动词 see, watch, observe, notice, look at, hear, listen to, smell, taste, feel + do 表示动作的完整性，真实性；+doing 表示动作的连续性，进行性
I saw him work in the garden yesterday.
昨天我看见他在花园里干活了。（强调 "我看见了" 这个事实）
I saw him working in the garden yesterday. （强调 "我见他正干活" 这个动作）
昨天我见他正在花园里干活。
典型例题
1 ）They knew her very well. They had seen her ___ up from childhood.
   A. grow B. grew C. was growing D. to grow
答案：A. 因题意为，他们看着她长大，因此强调的是成长的过程，而非正在长的动作，因此用 see sb do sth 的句型。
2 ）The missing boy was last seen ___ near the river.
A. playing B. to be playing C. play D. to play
答案 A. 本题强调其动作，正在河边玩，应此用 see sb. doing sth 句型。