已知下列命题中：
（1）若$k\in R$，且$k\overrightarrow{b}=\overrightarrow{0}$，则k=0或$\overrightarrow{b}=\overrightarrow{0}$，
（2）若$\overrightarrow{a}·\overrightarrow{b}=0$，则$\overrightarrow{a}=\overrightarrow{0}$或$\overrightarrow{b}=\overrightarrow{0}$
（3）若不平行的两个非零向量$\overrightarrow{a}$,$\overrightarrow{b}$，满足$\left|\overrightarrow{a}\right|=\left|\overrightarrow{b}\right|$，则$(\overrightarrow{a}+\overrightarrow{b})·(\overrightarrow{a}-\overrightarrow{b})=0$
（4）若$\overrightarrow{a}$与$\overrightarrow{b}$平行，则$\overrightarrow{a}·\overrightarrow{b}=\left|\overrightarrow{a}\right|·\left|\overrightarrow{b}\right|$其中真命题的个数是（  ）

下列说法中正确的是       （     ）

    I went with some colleagues from my office for a dinner in a very popular local restaurant. It was1business time and the restaurant was packed. We2found a table in a corner for three of us.

    As soon as we sat down, we heard a crash when a cleaning boy3the floor with all the plates he was carrying. There was_4and no one was saying or doing anything.

    In a flash I remembered my5many years ago. Once. I passed out in the airport because I had rushed there on my own on a(n)6_stomach I was7and taken care of by two strangers. Now this was my chance to8it forward.

    I ran to the young man's side immediately, turned him on his back and screamed for someone to9a hot drink. Soon people started asking if I was a doctor. I said I was not,10I was skillful at blacking out (晕厥).

    The kid soon opened his eyes,11what had happened. I12him by saying it was OK and I had had a13 experience. He had not eaten anything. I held the14_drink to his mouth till he finished it and sat with him till he felt OK. By then the15had arrived. I asked her to give the kid something to eat. I offered to pay.

    The manager was kind enough to refuse the16and agreed to make sure the kid ate before he went home. By the time all this was17_, it was getting late for my colleagues. Since we hadn't18anything yet, they decided to go home.

    I slowly walked home, not hungry any more, feeling19for the opportunity I pay forward the20I had received many years ago.