Hãy dùng từ gợi ý viết hoàn chỉnh những câu sau:
1. You / know / who invent / ballpoint pen ?
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2. When / I / primary school / teacher / make / me / write / fountain-pen.
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3. At / time / I / prefer / use / ballpoint pen.
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4. Ballpoint pens / use / to / very expensive / when / first introduce / Viet Nam.
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5. Father / say / ballpoint pen / used / cost / some VND.
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6. Big / French company / make / ballpoint pens / call / Bic.
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7. How many / ballpoint pens / produce / world / each year?
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8. Ballpoint pens / use / widely / than / fountainpens.
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9. It / because / they / cheaper / and / convenient.
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10. It / advisable / that / children / learn / write / not use / ballpoint pens.
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