Apart from pronunciation and different sets of vocabularies preferred by Chinese speakers from different regions, one reason why spoken Chinese is not easy to learn is precisely due to the lack of tenses. For English speakers, the information normally given through tenses seems to be "missing" in Chinese, and it makes building Chinese sentences difficult.
There are many many ways to communicate the "missing information" about time. We often use one of these three ways:
- time words, adverbs and auxiliary verbs
Getting used to them takes time. Let's take a closer look at how Chinese operates without tenses yet works perfectly fine with these devices.
1. time words, adverbs and auxiliary verbs
Chinese verbs does not have tense. However, in situations where the information about time is necessary, we can simply use time words, adverbs and auxiliary verbs to make the distinction.
Wǒ yǐqián shì lǎoshī.
I-previously-be-teacher. (I was a teacher previously.)
Wǒ xiànzài shì dàxuéshēng.
I-now-be-college student. (I am a college student now.)
Qùnián wǒ qù Běijīng xuéxí Zhōngwén.
Last year-I-go-Beijing-study-Chinese. (I went to Beijing to study Chinese last year.)
Wǒ yào qù Běijīng xuéxí.
I-will-go-Beijing-study. (I am going to Beijing to study.)
In Chinese, we often mark verbs with particular particles to show the "aspect" of them. Here are some common particles:
-guo: have the experience of doing
-le: complete the action of doing
-zhe: while doing, in the middle of doing
Here are some examples:
Wǒ chīguo lāmiàn.
I-have the experience of eating-ramen. (I have tried ramen before.)
Wǒ chīle sānwǎn mǐfàn.
I-complete the action of eating-three bowls of-rice. (I had three bowls of rice.)
Wǒ zuòzhe chī.
I-sitting-eat. (I ate/eat while sitting.)
Aspect markers, especially the -le, are particularly hard for learners to master.
A lot of sentences are ambiguous by itself (for English speakers!) but would be crystal clear when used in context. In the real world, a spoken sentence always comes with a context. Let's take a look at this sentence as example:
Wǒ chīle wǔfàn jiù qù gōngsī.
Without a context, this sentence kind of "floats in the air," waiting to be matched to whatever you have in mind.
If your coworker is waiting for you impatiently in your office, and you text her saying "Wǒ chīle wǔfàn jiù qù gōngsī!" Obviously, the translation would be "I will go to the company after lunch!"
If you are telling your friend about how your typical day goes, saying "Wǒ chīle wǔfàn jiù qù gōngsī." would mean "I go to the company after lunch."
If you are writing a diary for the day, you may as well write "Wǒ chīle wǔfàn jiù qù gōngsī." In this situation, the sentence should be translated as "I went to the company after lunch."
Some students take -le as a past tense marker since it is about "completion." However, the English translation varies depending on the context. You can complete something in the past, your can also get things completed in the future.
As you may see, mastering how and when to use these devices to communicate information about time could take lots of time! On the other hand, just like you mentioned in your question, I do think the lack of plurals in Chinese actually makes Chinese a bit easier to learn (we do have a plural suffix -men, but the use is pretty limited.) However, there is still a whole system of measure words to be memorized for learners just to count things properly...
Every language has its strange quirks. But that is probably one of the many reasons why learning new languages broadens our horizon and brings us new perspectives :)