填空

填 tián HSK 4 #2,514

to fill in; to fill out / to stuff; to cram

航空 hángkōng HSK 4 #3,096

aviation / air (as modifier, e.g. airmail, airline)

空间 kōngjiān HSK 4 #1,780

space / room

填补 tiánbǔ HSK 7-9 #9,373

to fill (a gap) / to make up for (a deficiency)

空白 kòngbái HSK 7-9 #5,994

blank space / gap / void

填写 tiánxiě HSK 7-9 #12,838

to fill in; to fill out (a form)

天空 tiānkōng HSK 3 #3,009

sky

填志愿 tiánzhìyuàn

to fill in university/college preferences (after gaokao) / to submit one's application choices

空档 kòngdàng

gap (between objects) / interval of time between events / free slot (in a schedule) / (figurative) market gap

填词 tiáncí #36,280

to write lyrics for an existing tune / to compose a ci poem (in a fixed metrical pattern) / to fill in lyrics