In user-level threads, a system call by a thread may block all other threads of the process. Explain why

3. what is the output of the following statements? temporary object1; temporary object2("rectangle", 8.5, 5); temporary object3("circle", 6, 0); temporary object4("cylinder", 6, 3.5); cout < < fixed < < showpoint < < setprecision(2); object1.print(); object2.print(); object3.print(); object4.print(); object1.set("sphere", 4.5, 0); object1.print();