Randolph Smith and Kenneth House ____________ (develop) the first battery-operated smoke detectors for homes. Today, smoke detectors ______________ (require) in homes, schools, and apartment buildings.
Randolph Smith and Kenneth House developed the first battery-operated smoke detectors for homes. Today, smoke detectors are required in homes, schools, and apar
The microwave oven ______________ (invent) by Perry Spencer in 1947. The first microwave ovens ____________ (weigh) 750 pounds and ____________ (cost) $5,000.
The microwave oven was invented by Perry Spencer in 1947. The first microwave ovens weighed 750 pounds and cost $5,000.
Charles Goodyear ______________ (make) the first sneakers in 1917.
Charles Goodyear made the first sneakers in 1917.
The pop-top can ______________ (develop) by Ermal Fraze. The top and the ring ____________ (stay) attached and ______________ (negative cause) litter. Before 1973, soda ____________ (bottle) in glass bottles. Then, Nathaniel Wyeth _________
The pop-top can was developed by Ermal Fraze. The top and the ring stayed attached and negatively caused litter. Before 1973, soda was bottled in glass bottles.
Roy Plunkett ____________ (invent) Teflon in 1946. Teflon ______________ (apply) to cookware eight years later. Many cooks now ____________ (use) non-stick and pans.
Roy Plunkett invented Teflon in 1946. Teflon was applied to cookware eight years later. Many cooks now use non-stick and pans.
VCRs ______________ (introduce) in 1971. They ____________ (allow) families to rent movies at video stores. In 1995, many companies ____________ (work) together to develop DVD technology. Today, more DVD machines ______________ (sell) than
VCRs were introduced in 1971. They allowed families to rent movies at video stores. In 1995, many companies worked together to develop DVD technology. Today, mo
Velcro ______________ (invent) by George de Mestral. It ______________ (use) to fasten two materials together. Many companies ____________ (use) Velcro on their clothing products.
Velcro was invented by George de Mestral. It was used to fasten two materials together. Many companies use Velcro on their clothing products.