I enjoy go go​ing ca​mping with m​y husband. We can enjoy the beautiful scenery by having a really yummy barbeque. I can't miss to drink​ drinking soju. It really makes me happy.  

1) I'm supposed to stay at H hotel. / I'm planning to stay at H hotel. -> I'm staying at the H hotel.​​

=> Another way: Your sentence is okay and this is another way of saying it.

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2) I will stay in my cousin's apartment. ->​​I am staying at my cousins' apartment.​

​=> Another way: Your sentence is okay and this is another way of saying it.

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3) Do you have something to make a declaration? ->​​Do you have anything to declare?

​=> Another way: Your sentence is okay and this is another way of saying it.​​​​​​