2 no difference
3 no difference although b sounds more temporary
4 In a, we know the listener studied with Professor Robson. This question asks if the listener also studied with Robson at a time before this more recent time. In b, the speaker asks if the listener has ever studied with Professor Robson. He/She knows that the other person is studying with him now, and is asking if this is the first time.
5 In a, the task is finished. In b, the task is not finished. The emphasis is on the activity in progress.
1 What do you hope to have achieved by the time you’re eighty?
3 By 2030, how long will you have been working?
5 How long have you known your best friend?
Civil liberties are civil rights and freedoms that provide an individual
with specific rights. Though the scope of the term differs amongst
various countries, some examples of civil liberties include the freedom
from slavery and forced labor, freedom from torture and death, the right to liberty and security, freedom of conscience, religion, expression, press, assembly and association, speech, the right to privacy, the right to equal treatment and the right to a fair trial, as well as the right to life. Other civil liberties may also include the right to own property, the right to defend oneself, and the right to bodily integrity.
Freedom of speech
human rights: the basic rights that everyone has to say what they think, vote, be treated fairly, etc.
child labour: the regular and sustained employment of children (it is illegal in many countries)
economic development: the process of improving the financial situation of a place (often a country)
intellectual property: the product of an intellectual activity (e.g. in artistic or commercial fields) that nobody else can legally copy
capital punishment: the practice of killing someone who has committed a serious crime
religious freedom: the ability to practise any religion that you choose, without being arrested or otherwise persecuted
environmental awareness: understanding of problems related to the land, water and air on Earth
illegal immigration: when people cross international borders in a way that breaks the immigration laws of the destination country
civil liberties: the right of all citizens to be free to do what they want while respecting the rights of other people
free trade: a situation in which the goods coming into or going out of a country are not controlled or taxed
freedom of speech: the ability to say what you wish without being censored
gun control: laws that limit the ways in which guns can be sold, owned and used
2 human rights
3 free trade
4 freedom of speech
5 religious freedom
6 illegal immigration
7 intellectual property
8 gun control
9 environmental awareness
10 capital punishment
11 economic development
12 child labour
b gender inequality
c antisocial behavior
d white-collar crime
g organised crime
h ageism /ˈeɪdʒɪzəm/ unfair treatment of people because they are considered too old. E.g. ageism in job advertisements.
tackle something to make a determined effort to deal with a difficult problem or situation. E.g. The government is determined to tackle inflation. I think I'll tackle the repairs next weekend. Firefighters tackled a blaze in a garage last night. Police have launched an initiative to tackle rising crime.