Is it worth participating in demonstrations against a system or a person in a country where there is no sense of democracy?

In general, i think that if the majority of society are not satisfy with the situation, it is their right to express their request and unfortunately, most of the time you should say your request in loud voice. More over, the type of government doesn't affect on taking participate in demonstration. However, mostly when there is no sense of democracy the general condition is intolerable and necessity of demonstration is remarkable.

On the other hand, demonstration against one system or person, for another system or person who has no advantage in compare with first one is worthless! and participating in such strike will be kind of stupidity. So, you should know what you want, and you should consider the consequences of your petition.
On the whole, right is achievable. without considering who might be annoyed, you should fight for you ambitions.

Some job's phrasal verbs!

I'm up to my ear in work.
= I am very busy!

Are you on a loose end this evening?
= Are you free this evening?

I've already got enough on my plate!
= I have enough work to do!

I can fit you in on Monday.
= I can be instead of you on Monday.

I'm tied up till after lunch.
= I am terribly busy till after lunch.

Before leaving, I have to clock out.
it is clear!

Do you think workers ought to be allowed to go on strike?

In general, I think that workers should be allowed to go on strike when ever they want. Especially in large factories sometimes employers don’t know exactly about their workers condition because between them and their workers are lots of middle men who might not be able to transfer all of the information to the employers.
On the other hand, we shouldn’t allow workers feel free to go on strike because of everything that they think it is wrong. It may cause anarchic situation in the organization and it is obvious that you can’t rely on everything in hesitated environment.
In the end, it is a matter of compromise. All the employers and employees in every work place should find their own way to get well with each other because both of them need the others in order to achieve prosperity.