A man looks through a microscope while another man in the background also looks through a microscope.
The men are looking through a microscope.
When two or more people are doing the same action the plural of man which is men can be used.
exists e1 p1 x1 x2 x4.(n_background(x4) & exists e2 s1 x3 x5.(a_also(s1) & Manner(e2,s1) & through(e2,x5) & n_microscope(x5) & Actor(e2,x3) & v_look(e2) & in(x3,x4) & n_man(x3) & -(x3 = x1)) & n_man(x1) & n_man(x1) & while(e1,p1) & through(e1,x2) & n_microscope(x2) & Actor(e1,x1) & v_look(e1))
exists e1 x1 x2.(n_man(x1) & through(e1,x2) & n_microscope(x2) & Actor(e1,x1) & v_look(e1))