Xiaoyu's parcel was due yesterday. She calls the driver, who is already on the road.
Xiaoyu
喂，您好，我的包裹还没到。
Wèi, nín hǎo, wǒ de bāoguǒ hái méi dào.
Hello, my parcel has not arrived.
The delivery driver
您的单号是多少？
Nín de dān hào shì duōshao ?
What is your tracking number?
Xiaoyu
后面四位是三八二九。
Hòumian sì wèi shì sān bā èr jiǔ.
The last four digits are 3829.
The delivery driver
我查一下。您的东西正在路上。
Wǒ chá yīxià. Nín de dōngxi zhèngzài lù shàng.
Let me check. Your item is on its way.
Xiaoyu
网上说昨天下午就该到了。
Wǎng shàng shuō zuótiān xiàwǔ jiù gāi dào le.
The website said it was due yesterday afternoon.
The delivery driver
因为下大雨，所以昨天的车都晚了。
Yīnwèi xià dàyǔ, suǒyǐ zuótiān de chē dōu wǎn le.
It was raining hard, so all of yesterday's vans ran late.
Xiaoyu
那今天几点能送到？
Nà jīntiān jǐ diǎn néng sòng dào ?
What time can you deliver it today?
The delivery driver
我正在送，大概两个小时以后。
Wǒ zhèngzài sòng, dàgài liǎng gè xiǎoshí yǐhòu.
I am out on the round now, in about two hours.
Xiaoyu
我下午三点要出去，能不能早一点儿？
Wǒ xiàwǔ sān diǎn yào chūqù, néng bùnéng zǎo yīdiǎnr ?
I have to go out at three, could you make it a bit earlier?
The delivery driver
那我先送您这一件，四十分钟左右。
Nà wǒ xiān sòng nín zhè yī jiàn, sìshí fēnzhōng zuǒyòu.
Then I will bring yours first, in about forty minutes.
Xiaoyu
谢谢您，我在家等着。
Xièxie nín, wǒ zài jiā děng zhe.
Thank you, I will be waiting at home.
正在 goes before the verb and says the action is under way at this very moment: 我正在送, I am out delivering. You also meet 在 on its own, lighter, and 呢 at the end of the sentence, which is enough in speech: 他吃饭呢. The three often combine, 正在…呢, but neither 正在 nor 呢 goes with 了, which says the opposite: a finished action.
English picks one: "because it was raining" or "so they were late". Chinese puts both markers, 因为 before the cause and 所以 before the consequence, and keeping both is not heavy-handed: it is the normal form. You may drop 因为 when the cause comes first, but never 所以.
An expected action is negated with 还没, not yet, and never with 不: 还没到, it has not arrived yet, with the implication that it should have. Facing it, 该…了 says what ought to have happened: 就该到了, it should have been here by now. The two turns of phrase answer each other in every complaint.
