根据短文内容，请将单词填写在题号对应的横线上。

    Tins of cooling ointment (清凉油) have become a currency for Chinese traveling in Egypt.

    ____ (visit)the complex of ancient temples at Karnak, Chinese tourist Mr. Ye lost his way among the stone churches and pillars.

    An Egyptian guide gave him directions. To show his ____ (appreciate), Mr. Ye handed him a small red tin the size of a large coin. Inside ____ (be) a cooling ointment that has the function of refreshing mind and preventing pain. Mr. Ye brought 50 tins with him on his six-day tour to hand out as tips.

    "Before I came to Egypt, the tourism agency told me ____ (repeat) to bring cooling balm as a gift to make the trip ____ (easy)," said Mr. Ye, a 25-year-old ____ family sells Chinese medicine online. Egyptians, he said, are very nice to Chinese tourists, ____ they love this little gift."

    Egyptians sometimes demand the balm by running a thumb across their foreheads. Li Xiaodong, an Egyptologist at China's Northeast Normal University, believes Chinese travelers initially brought cooling balm for ____ (person) use because it's very hot in Egypt, then ____ (discover) Egyptians liked it.

    Some Chinese tourists said giving gifts feels better than handing over money. "If you give essential balm, ____ is more like you're giving it to friends," said one Chinese tourist.

设N_A表示阿伏加德罗常数，下列叙述中正确的是（   ）

（1）下列物质中：互为同素异形体的有　 ____　 （填序号，下同），属于同位素的有　 ____　，属于同一种物质的有　 ____　．

①液氯   ②$\stackrel{35}{17}$Cl  ③白磷   ④氯气   ⑤红磷   ⑥$\stackrel{37}{17}$​Cl

（2）下列物质中：只存在共价键的是　 ____　（填序号，下同），只存在离子键的是　 ____　，既存在离子键又存在极性共价键的是　 ____　，既存在离子键又存在非极性共价键的是 ____　．

①Ar     ②CO₂    ③Na₂O₂④KOH     ⑤MgBr₂     ⑥NH₄Cl     ⑦CaO    ⑧H₂SO₄

（3）用电子式表示MgBr₂的形成过程： ____