Because there is none. Why did this happen? Why did this happen? Please make sure your browser supports JavaScript and cookies and that you are not blocking them from loading. Please make sure your browser supports JavaScript and cookies and that you are not blocking them from loading.
because there is none. They did this happen.
( z0 multi-sentence :snt ( z1 cause :ARG0 ( z2 none ) ) :snt ( z3 do :ARG0 ( z4 they ) :ARG1 ( z5 this ) ) )
(z0 / multi-sentence
    :snt1 (z1 / cause-01
              :ARG0 (z2 / none))
    :snt2 (z3 / do-02
              :ARG0 (z4 / they)
              :ARG1 (z5 / this)))
because there is none . They did this happen .
z1 :ARG0 z2
z0 :snt1 z1
z3 :ARG0 z4
z0 :snt2 z3
z3 :ARG1 z5