The correct answer is: D. We can gain nothing without labour.
The sentence “Nothing can be gained without labour” means that in order to achieve anything, we must put in the effort. This is true in all aspects of life, from learning a new skill to building a successful career. Without hard work, we will not be able to achieve our goals.
The other options are incorrect because they do not accurately reflect the meaning of the sentence. Option A, “We could gain nothing without labour,” is too weak. It suggests that it is possible to gain something without labour, but that it would be difficult. Option B, “We cannot gain nothing without labour,” is grammatically incorrect. Option C, “We should gain nothing without labour,” is too moralistic. It suggests that we are obligated to work hard, even if we don’t want to.
In conclusion, the correct answer is: D. We can gain nothing without labour. This means that in order to achieve anything, we must put in the effort. This is true in all aspects of life, from learning a new skill to building a successful career. Without hard work, we will not be able to achieve our goals.