even 通常指平面上的各点或一条直线的各点处在同一平面或直线上。
flat 指光滑平整的表面，但不一定是水平的。
level 强调没有高低之处，且在同一水平面，可引申指才能相等或与相邻某物平行。
smooth 侧重指表面十分平滑，无任何粗糙的感觉。引申作圆滑解。
参考例句
1. The Earth is round, not flat. 地球是圆的，不是扁平的。
2. It gets flat. 它变成平的。
3. The world is flat, but not fair, because of opportunity! 世界是平的，却是不公平的，因为有“机会”！
英英解释
n.
1. a level tract of land
2. a shallow box in which seedlings are started
3. a musical notation indicating one half step lower than the note named
4. freight car without permanent sides or roof
5. a deflated pneumatic tire
6. scenery consisting of a wooden frame covered with painted canvas; part of a stage setting
7. a suite of rooms usually on one floor of an apartment house adj.
1. having a surface without slope, tilt in which no part is higher or lower than another
2. having a relatively broad surface in relation to depth or thickness
3. not modified or restricted by reservations
4. stretched out and lying at full length along the ground
5. lacking contrast or shading between tones
6. lowered in pitch by one chromatic semitone
7. flattened laterally along the whole length (e.g., certain leafstalks or flatfishes)
8. lacking taste or flavor or tang
9. lacking stimulating characteristics; uninteresting
10. having lost effervescence
11. (of taxes) not increasing as the amount taxed increases
12. sounded or spoken in a tone unvarying in pitch
13. horizontally level
14. lacking the expected range or depth; not designed to give an illusion or depth
15. (of a tire) completely or partially deflated
16. not reflecting light; not glossy
17. commercially inactive adv.
1. with flat sails
2. in a forthright manner; candidly or frankly
