In Chinese Pinyin System, the neutral tone (also called toneless) is a special sandhi for the four tones. It is normally pronounced short and light in special conditions, and it's usually unmarked.
Auxiliary words like 的(de), 地(de), 得(de), 着(zhe), 了(le), 过(guo) and mood words like 吧(ba), 嘛(ma), 呢(ne), 啊(a) are all in neutral tone.
领路的 [lead the way]：lǐnglùde
愉快地 [agreeably]：yúkuàide
学得(好) [learn (well)]：xuéde(hǎo)
笑着 [on the laugh]：xiàozhe
活了 [living]：huóle
算了吧 [well, all right]：suànleba
The ending word of reduplicated words and the same double verbs are in neutral tone.
妈妈 [mom]：māma
弟弟 [little brother]：dìdi
看看 [have a look]：kànkan
等等 [wait]：děngdeng
了解了解 [to know about it]：liǎojiēliǎojie
Imaginary morphemes for word-building like 子(zi), 头(tou) and some words expressing groups like 们(men) are in neutral tone.
鸽子 [dove]：gēzi
燕子 [swallow]：yànzi
馒头 [steamed bread]：mántou
木头 [wood]：mùtou
我们 [we]：wǒmen
女士们 [ladies]：nǚshìmen
Some morphemes or words behind nouns or pronouns expressing position like 上(shang), 面(mian), 边(bian), 里(li) are in neutral tone.
路上 [on the road]：lùshang
脸上 [on the face]：liǎnshang
外面 [outside]：wàimian
后面 [back, rear]：hòumian
这边 [here, this side]：zhèbian
右边 [right]：yòubian
村里 [in the village]：cūnli
屋里 [in the room]：wūli
Some directional words behind verbs and adjectives like 来(lai), 去(qu) are in neutral tone.
进来 [come in]：jìnlai
起来 [up (with)]：qǐlai
出来 [come out]：chūlai
进去 [go in]：jìnqu
出去 [go out]：chūqu
上去 [get on]：shàngqu
The measure word 个(ge) is in neutral tone.
这个 [this one]：zhège
那个 [that one]：nàge
一个 [one, a]：yīge
两个 [two, a couple of]：liǎnge
三个 [three]：sānge
四个 [four]：sìge
五个 [five]：wǔge
六个 [six]：liùge
七个 [seven]：qīge
八个 [eight]：bāge
九个 [nine]：jiǔge
十个 [ten]：shíge
Some everyday double syllables have the second syllable usually in neutral tone.
爱人 [lover]：àiren
本事 [ability]：běnshi
苍蝇 [fly]：cāngying
东家 [boss]：dōngjia
房子 [house]：fángzi
怪物 [monster]：guàiwu
狐狸 [fox]：húli
困难 [difficulty]：kùnnan
老婆 [wife]：lǎopo
哑巴 [dummy]：yǎba
嘴巴 [mouth]：zuǐba
Some syllables in neutral tone can make a distinction and tell the difference of part of speech.
We do things properly, not be careless.
You haven't got the general effect of this paper.