Infinitive and gerund phrases

Which of the following sentences is written correctly?

• It's inappropriate to talk about politics at work or school.

• It's to talk about politics inappropriate at work or school.

• It's inappropriate at work or school to talk about politics.

(a)   (use) certain gestures is impolite in foreign countries.

What is another way to say: "asking someone's age is often considered rude"?

• To ask someone's age is considered rude often.

• Asking someone's age rude is often considered.

• It's often considered rude to ask someone's age.

It's not unusual in the United States (a)   (address) a professor by his or her first name.

What is customary in many cultures?

• Huging friends when you greet them.

• Hugging friends when you greet them.

• To hug friends when you greet them.

Choose the sentence(s) that is written in the proper order.

• Asking strangers if they are married is inappropriate in some countries.

• Asking strangers is inappropriate if they are married in some countries.

• It's inappropriate in some countries to ask strangers if they're married.